Team ID:6

Team member:Brendan Paul Voges, Raghuram Palaniappan, Shih-Chi Chen, Xianzheng Sun

# Read in the data and do some initial checking
mydata = read.table("Earnings.txt", header=TRUE)
dim(mydata)
## [1] 595  12
n = dim(mydata)[1]
p = dim(mydata)[2]

# Create each X predictor variable and Y response variable
x1.exp=mydata$experience
x2.weeks=mydata$weeks
x10.education=mydata$education
YM=mydata$wage

# categorical variable: occupation (Set occupation white=1, otherwise=0)
index3 = which(mydata$occupation=='white')
mydata$occupation[index3] = 1
mydata$occupation[-index3] = 0

# categorical variable: industry (Set industry yes=1, otherwise=0)
index4 = which(mydata$industry=='yes')
mydata$industry[index4] = 1
mydata$industry[-index4] = 0

# categorical variable: south (Set south yes=1, otherwise=0)
index5 = which(mydata$south=='yes')
mydata$south[index5] = 1
mydata$south[-index5] = 0

# categorical variable: smsa (Set smsa yes=1, otherwise=0)
index6 = which(mydata$smsa=='yes')
mydata$smsa[index6] = 1
mydata$smsa[-index6] = 0

# categorical variable: married (Set married yes=1, otherwise=0)
index7 = which(mydata$married=='yes')
mydata$married[index7] = 1
mydata$married[-index7] = 0

# categorical variable: gender (Set gender male=1, otherwise=0)
index8 = which(mydata$gender=='male')
mydata$gender[index8] = 1
mydata$gender[-index8] = 0

# categorical variable: union (Set union yes=1, otherwise=0)
index9 = which(mydata$union=='yes')
mydata$union[index9] = 1
mydata$union[-index9] = 0

# categorical variable: ethnicity (Set ethnicity afam=1, otherwise=0)
index11 = which(mydata$ethnicity=='afam')
mydata$ethnicity[index11] = 1
mydata$ethnicity[-index11] = 0
#############################
##### Data exploration 
#############################
head(mydata)
##   experience weeks occupation industry south smsa married gender union
## 1          9    32          1        1     1    0       1      1     0
## 2         36    30          0        1     0    0       1      1     0
## 3         12    46          0        1     0    0       0      1     1
## 4         37    46          0        0     0    1       0      0     0
## 5         16    49          1        0     0    0       1      1     0
## 6         32    47          0        1     0    1       1      1     0
##   education ethnicity wage
## 1         9         0  515
## 2        11         0  912
## 3        12         0  954
## 4        10         1  751
## 5        16         0 1474
## 6        12         0 1539
plot(mydata[,1:12])

model1 = lm(YM~., data=mydata[,1:12])
plot(model1)

library(MASS)
boxcox(model1)

####### data splitting
set.seed(111)  # include set.seed for reproducibility
ids = sample(1:595, 298)
# pseudo code
training = mydata[ids,]
validation = mydata[-ids,]

The largest \(R{a,p}=0.3543545\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11)

#######################################################################
##### Model selection: best subsets 
##### first-order models on X1 - X11
#######################################################################
library(leaps)
mydata1 = data.frame(cbind(YM,mydata[,1:11]))
models=regsubsets(YM~., data=mydata1,nbest=20)

# which variables are in the model
summary(models)$which
##   (Intercept) experience weeks occupation1 industry1 south1 smsa1 married1
## 1        TRUE      FALSE FALSE       FALSE     FALSE  FALSE FALSE    FALSE
## 1        TRUE      FALSE FALSE        TRUE     FALSE  FALSE FALSE    FALSE
## 1        TRUE      FALSE FALSE       FALSE     FALSE  FALSE FALSE    FALSE
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##   gender1 union1 education ethnicity1
## 1   FALSE  FALSE      TRUE      FALSE
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# find the Rp squared
Rp =summary(models)$rsq
p = rowSums(summary(models)$which)
# plot Rp squared
plot(p,Rp)

The largest \(R_{a,p}= 0.3455402671\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11)

# find the max Rap
Rap =summary(models)$adjr2
which.max(Rap) #132
## [1] 132
summary(models)$which[which.max(Rap),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
#plot Rap
plot(p,Rap)

The smallest \(C_p=8.864002\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11)

# find min cp
Cp =summary(models)$cp
which.min(Cp) #132
## [1] 132
summary(models)$which[which.min(Cp),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
which.min(Cp-p) #132
##   8 
## 132
summary(models)$which[which.min(Cp-p),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
#plot cp
p = rowSums(summary(models)$which)
plot(p,Cp) # we can see the smallest the cp is close to the p
abline(0,1)

The smallest \(SSE=108168963\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11) The smallest \(AIC=7223.833\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11) The smallest \(BIC=7259.454\), which is model:(X1,X3,X6,X8,X10,X11)

SSE = summary(models)$rss
which.min(SSE) #132
## [1] 132
summary(models)$which[which.min(SSE),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
AIC = n*log(SSE)-n*log(n)+2*p
BIC = n*log(SSE)-n*log(n)+p*log(n)

which.min(AIC) #132
##   8 
## 132
summary(models)$which[which.min(AIC),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
which.min(BIC) #92
##  6 
## 92
summary(models)$which[which.min(BIC),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE       FALSE       FALSE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
#plot AIC,BIC
plot(p,AIC) # we can see the smallest AIC is p=9

plot(p,BIC) # we can see the smallest BIC is p=7

The smallest \(PRESS=111072298\), which is model:(X1,X3,X4,X5,X6,X8,X10,X11)

include = summary(models)$which[,-1]
m = dim(include)[1]
PRESS = rep(0,m)
for (i in 1:m){
  temp = which(include[i,])
  reg = lm(YM~., data=data.frame(cbind(YM,mydata[,temp])))
  PRESS[i] = sum((reg$residuals/(1 - lm.influence(reg)$hat))^2)
}
which.min(PRESS) #132
## [1] 132
summary(models)$which[which.min(PRESS),]
## (Intercept)  experience       weeks occupation1   industry1      south1 
##        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
##       smsa1    married1     gender1      union1   education  ethnicity1 
##        TRUE       FALSE        TRUE       FALSE        TRUE        TRUE
#plot PRESS
plot(p, PRESS)

From each criterion, we select these two models:

#select the good models of first-order models.
i= 92
temp = which(include[i,])
sel1 = lm(YM~., data=data.frame(cbind(YM,mydata[,temp])))

i = 132
temp = which(include[i,])
sel2 = lm(YM~., data=data.frame(cbind(YM,mydata[,temp])))
#########################################################################
##### Model selection: best subsets 
##### First-order models and models with two-way interactions
#########################################################################

### models with two-way interactions
mydata2 = data.frame(cbind(YM,mydata[,1:11]))
model2= lm(YM~.^2, data=mydata2)
summary(model2)
## 
## Call:
## lm(formula = YM ~ .^2, data = mydata2)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1003.8  -213.7   -25.9   155.1  3268.8 
## 
## Coefficients:
##                          Estimate Std. Error t value Pr(>|t|)   
## (Intercept)            -7.449e+02  1.487e+03  -0.501  0.61664   
## experience              2.186e+01  2.186e+01   1.000  0.31781   
## weeks                   7.381e+00  2.940e+01   0.251  0.80189   
## occupation1            -8.173e+02  6.627e+02  -1.233  0.21802   
## industry1               2.166e+02  5.517e+02   0.393  0.69479   
## south1                  1.003e+03  5.313e+02   1.888  0.05955 . 
## smsa1                   5.009e+02  5.364e+02   0.934  0.35086   
## married1               -1.478e+03  1.038e+03  -1.423  0.15528   
## gender1                 1.602e+03  1.001e+03   1.600  0.11020   
## union1                  1.208e+03  5.770e+02   2.093  0.03684 * 
## education               3.464e+01  1.029e+02   0.337  0.73651   
## ethnicity1             -6.543e+01  9.758e+02  -0.067  0.94656   
## experience:weeks       -4.651e-01  3.939e-01  -1.181  0.23829   
## experience:occupation1  6.081e+00  4.780e+00   1.272  0.20392   
## experience:industry1   -3.223e-01  3.787e+00  -0.085  0.93221   
## experience:south1      -5.065e-01  4.384e+00  -0.116  0.90807   
## experience:smsa1        1.078e+00  4.013e+00   0.269  0.78827   
## experience:married1    -4.836e+00  6.813e+00  -0.710  0.47812   
## experience:gender1      8.075e+00  9.447e+00   0.855  0.39307   
## experience:union1      -3.395e+00  4.465e+00  -0.761  0.44728   
## experience:education    3.091e-03  8.275e-01   0.004  0.99702   
## experience:ethnicity1  -7.168e+00  7.676e+00  -0.934  0.35083   
## weeks:occupation1       9.437e+00  1.228e+01   0.768  0.44255   
## weeks:industry1        -2.022e+00  9.386e+00  -0.215  0.82953   
## weeks:south1           -6.870e+00  8.753e+00  -0.785  0.43288   
## weeks:smsa1            -8.398e+00  8.820e+00  -0.952  0.34145   
## weeks:married1          3.987e+01  1.351e+01   2.950  0.00331 **
## weeks:gender1          -3.526e+01  1.601e+01  -2.202  0.02811 * 
## weeks:union1           -1.277e+00  9.095e+00  -0.140  0.88838   
## weeks:education         7.587e-01  2.019e+00   0.376  0.70726   
## weeks:ethnicity1        1.135e+01  1.855e+01   0.612  0.54108   
## occupation1:industry1   6.487e+00  1.085e+02   0.060  0.95235   
## occupation1:south1      1.620e+01  1.121e+02   0.145  0.88513   
## occupation1:smsa1      -2.445e+01  1.111e+02  -0.220  0.82593   
## occupation1:married1   -9.027e+01  2.274e+02  -0.397  0.69158   
## occupation1:gender1     6.534e+01  2.755e+02   0.237  0.81260   
## occupation1:union1     -1.788e+02  1.160e+02  -1.542  0.12369   
## occupation1:education   3.817e+01  2.016e+01   1.894  0.05884 . 
## occupation1:ethnicity1 -1.025e+02  2.021e+02  -0.507  0.61216   
## industry1:south1       -1.994e+02  9.559e+01  -2.086  0.03746 * 
## industry1:smsa1        -1.316e+02  8.701e+01  -1.512  0.13108   
## industry1:married1      5.612e+01  1.503e+02   0.373  0.70899   
## industry1:gender1      -1.369e+02  2.262e+02  -0.605  0.54535   
## industry1:union1       -2.160e+02  9.466e+01  -2.282  0.02291 * 
## industry1:education     1.465e+01  1.974e+01   0.742  0.45843   
## industry1:ethnicity1    1.919e+02  1.774e+02   1.082  0.27964   
## south1:smsa1           -5.662e+01  9.249e+01  -0.612  0.54067   
## south1:married1        -3.887e+01  1.566e+02  -0.248  0.80410   
## south1:gender1          6.854e+01  1.953e+02   0.351  0.72571   
## south1:union1          -8.530e+00  1.090e+02  -0.078  0.93767   
## south1:education       -5.219e+01  2.008e+01  -2.599  0.00960 **
## south1:ethnicity1      -1.411e+01  1.919e+02  -0.074  0.94142   
## smsa1:married1          3.095e+01  1.464e+02   0.211  0.83261   
## smsa1:gender1           1.894e+02  2.070e+02   0.915  0.36067   
## smsa1:union1           -1.179e+02  9.857e+01  -1.196  0.23216   
## smsa1:education        -1.850e+00  1.996e+01  -0.093  0.92619   
## smsa1:ethnicity1       -9.783e+01  2.832e+02  -0.345  0.72987   
## married1:gender1       -1.612e+02  4.863e+02  -0.331  0.74046   
## married1:union1        -1.814e+02  1.731e+02  -1.048  0.29491   
## married1:education     -8.903e-01  3.997e+01  -0.022  0.98224   
## married1:ethnicity1     3.191e+02  2.915e+02   1.095  0.27420   
## gender1:union1          1.514e+02  2.231e+02   0.679  0.49766   
## gender1:education       4.197e+00  4.837e+01   0.087  0.93089   
## gender1:ethnicity1     -5.803e+02  3.216e+02  -1.804  0.07177 . 
## union1:education       -6.275e+01  2.287e+01  -2.744  0.00629 **
## union1:ethnicity1       1.228e+02  1.846e+02   0.665  0.50637   
## education:ethnicity1   -1.890e+01  3.739e+01  -0.505  0.61345   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 415.8 on 528 degrees of freedom
## Multiple R-squared:  0.455,  Adjusted R-squared:  0.3869 
## F-statistic: 6.679 on 66 and 528 DF,  p-value: < 2.2e-16

The smallest \(AIC=7175.75\), which is model: (X1,X2,X3,X4,X5,X6,X7,X8,X9,X10,X11,X1X2,X1X3,X1X11,X2X3,X2X7,X2X8,X3X9,X3X10,X4X5,X4X6,X4X9,X4X11,X5X19,X6X8,X7X11,X8X11,X9X10)

#Use step to find the smallest AIC model
library(leaps)
models =lm(YM~.^2,mydata2)
stepwise=step(models)
## Start:  AIC=7239
## YM ~ (experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity)^2
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:education   1         2 91306975 7237.0
## - married:education      1        86 91307059 7237.0
## - occupation:industry    1       618 91307591 7237.0
## - south:ethnicity        1       935 91307908 7237.0
## - south:union            1      1058 91308031 7237.0
## - experience:industry    1      1253 91308226 7237.0
## - gender:education       1      1302 91308275 7237.0
## - smsa:education         1      1486 91308459 7237.0
## - experience:south       1      2308 91309281 7237.0
## - weeks:union            1      3410 91310383 7237.0
## - occupation:south       1      3613 91310586 7237.0
## - smsa:married           1      7733 91314706 7237.1
## - weeks:industry         1      8024 91314997 7237.1
## - occupation:smsa        1      8372 91315345 7237.1
## - occupation:gender      1      9729 91316702 7237.1
## - south:married          1     10650 91317623 7237.1
## - experience:smsa        1     12485 91319458 7237.1
## - married:gender         1     18994 91325967 7237.1
## - smsa:ethnicity         1     20640 91327613 7237.1
## - south:gender           1     21308 91328281 7237.1
## - industry:married       1     24114 91331087 7237.2
## - weeks:education        1     24415 91331388 7237.2
## - occupation:married     1     27245 91334218 7237.2
## - education:ethnicity    1     44180 91351154 7237.3
## - occupation:ethnicity   1     44502 91351475 7237.3
## - industry:gender        1     63323 91370296 7237.4
## - weeks:ethnicity        1     64682 91371655 7237.4
## - south:smsa             1     64812 91371785 7237.4
## - union:ethnicity        1     76462 91383435 7237.5
## - gender:union           1     79645 91386618 7237.5
## - experience:married     1     87133 91394106 7237.6
## - industry:education     1     95204 91402177 7237.6
## - experience:union       1    100023 91406996 7237.7
## - weeks:occupation       1    102123 91409096 7237.7
## - weeks:south            1    106528 91413501 7237.7
## - experience:gender      1    126347 91433320 7237.8
## - smsa:gender            1    144747 91451720 7237.9
## - experience:ethnicity   1    150793 91457767 7238.0
## - weeks:smsa             1    156782 91463756 7238.0
## - married:union          1    190094 91497067 7238.2
## - industry:ethnicity     1    202542 91509515 7238.3
## - married:ethnicity      1    207185 91514158 7238.3
## - experience:weeks       1    241038 91548011 7238.6
## - smsa:union             1    247436 91554409 7238.6
## - experience:occupation  1    279817 91586790 7238.8
## <none>                               91306973 7239.0
## - industry:smsa          1    395448 91702421 7239.6
## - occupation:union       1    411142 91718115 7239.7
## - gender:ethnicity       1    562906 91869879 7240.7
## - occupation:education   1    620025 91926998 7241.0
## - industry:south         1    752501 92059474 7241.9
## - weeks:gender           1    838327 92145300 7242.4
## - industry:union         1    900259 92207232 7242.8
## - south:education        1   1168423 92475396 7244.6
## - union:education        1   1301618 92608591 7245.4
## - weeks:married          1   1505379 92812352 7246.7
## 
## Step:  AIC=7237
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:education + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:education      1        84 91307059 7235.0
## - occupation:industry    1       620 91307596 7235.0
## - south:ethnicity        1       933 91307908 7235.0
## - south:union            1      1057 91308032 7235.0
## - experience:industry    1      1257 91308232 7235.0
## - gender:education       1      1303 91308279 7235.0
## - smsa:education         1      1484 91308459 7235.0
## - experience:south       1      2390 91309365 7235.0
## - weeks:union            1      3421 91310396 7235.0
## - occupation:south       1      3633 91310609 7235.0
## - smsa:married           1      7732 91314707 7235.1
## - weeks:industry         1      8022 91314997 7235.1
## - occupation:smsa        1      8374 91315349 7235.1
## - occupation:gender      1      9727 91316703 7235.1
## - south:married          1     10653 91317628 7235.1
## - experience:smsa        1     12807 91319783 7235.1
## - married:gender         1     19081 91326057 7235.1
## - smsa:ethnicity         1     20653 91327629 7235.1
## - south:gender           1     21384 91328360 7235.1
## - industry:married       1     24263 91331238 7235.2
## - weeks:education        1     24543 91331519 7235.2
## - occupation:married     1     27348 91334324 7235.2
## - education:ethnicity    1     44392 91351368 7235.3
## - occupation:ethnicity   1     44500 91351475 7235.3
## - industry:gender        1     63586 91370561 7235.4
## - south:smsa             1     64843 91371818 7235.4
## - weeks:ethnicity        1     64860 91371835 7235.4
## - union:ethnicity        1     76486 91383462 7235.5
## - gender:union           1     79660 91386636 7235.5
## - experience:married     1     87333 91394308 7235.6
## - industry:education     1     95350 91402326 7235.6
## - experience:union       1    101742 91408718 7235.7
## - weeks:occupation       1    102533 91409509 7235.7
## - weeks:south            1    107228 91414204 7235.7
## - experience:gender      1    127006 91433981 7235.8
## - smsa:gender            1    144756 91451731 7235.9
## - experience:ethnicity   1    150947 91457923 7236.0
## - weeks:smsa             1    156782 91463758 7236.0
## - married:union          1    190407 91497382 7236.2
## - industry:ethnicity     1    202927 91509903 7236.3
## - married:ethnicity      1    207392 91514367 7236.3
## - experience:weeks       1    241189 91548164 7236.6
## - smsa:union             1    247669 91554645 7236.6
## <none>                               91306975 7237.0
## - industry:smsa          1    397490 91704466 7237.6
## - experience:occupation  1    410984 91717960 7237.7
## - occupation:union       1    422118 91729093 7237.7
## - gender:ethnicity       1    563265 91870240 7238.7
## - occupation:education   1    621310 91928286 7239.0
## - industry:south         1    754162 92061138 7239.9
## - weeks:gender           1    843006 92149982 7240.5
## - industry:union         1    904630 92211605 7240.9
## - south:education        1   1180347 92487322 7242.6
## - union:education        1   1318095 92625071 7243.5
## - weeks:married          1   1507936 92814912 7244.7
## 
## Step:  AIC=7235
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:industry    1       655 91307714 7233.0
## - south:ethnicity        1       938 91307997 7233.0
## - south:union            1      1043 91308102 7233.0
## - experience:industry    1      1318 91308377 7233.0
## - smsa:education         1      1460 91308519 7233.0
## - gender:education       1      2086 91309145 7233.0
## - experience:south       1      2376 91309435 7233.0
## - weeks:union            1      3408 91310467 7233.0
## - occupation:south       1      3698 91310757 7233.0
## - smsa:married           1      7696 91314755 7233.1
## - weeks:industry         1      8185 91315244 7233.1
## - occupation:smsa        1      8455 91315514 7233.1
## - south:married          1     10656 91317715 7233.1
## - experience:smsa        1     12992 91320051 7233.1
## - occupation:gender      1     15753 91322812 7233.1
## - married:gender         1     18998 91326057 7233.1
## - smsa:ethnicity         1     20570 91327629 7233.1
## - south:gender           1     21398 91328457 7233.1
## - weeks:education        1     24626 91331685 7233.2
## - industry:married       1     26885 91333944 7233.2
## - education:ethnicity    1     44479 91351538 7233.3
## - occupation:ethnicity   1     44751 91351810 7233.3
## - occupation:married     1     60906 91367965 7233.4
## - south:smsa             1     64928 91371987 7233.4
## - industry:gender        1     66135 91373194 7233.4
## - weeks:ethnicity        1     66321 91373380 7233.4
## - union:ethnicity        1     76698 91383757 7233.5
## - gender:union           1     79751 91386810 7233.5
## - experience:married     1     89098 91396157 7233.6
## - industry:education     1     95307 91402366 7233.6
## - experience:union       1    101844 91408903 7233.7
## - weeks:occupation       1    102452 91409511 7233.7
## - weeks:south            1    107633 91414692 7233.7
## - experience:gender      1    127691 91434750 7233.8
## - smsa:gender            1    144694 91451753 7233.9
## - experience:ethnicity   1    151353 91458412 7234.0
## - weeks:smsa             1    156729 91463788 7234.0
## - married:union          1    190406 91497465 7234.2
## - industry:ethnicity     1    202860 91509919 7234.3
## - married:ethnicity      1    236420 91543479 7234.5
## - experience:weeks       1    242203 91549262 7234.6
## - smsa:union             1    247678 91554737 7234.6
## <none>                               91307059 7235.0
## - industry:smsa          1    397407 91704467 7235.6
## - experience:occupation  1    410932 91717991 7235.7
## - occupation:union       1    422222 91729281 7235.7
## - gender:ethnicity       1    621670 91928729 7237.0
## - occupation:education   1    621762 91928821 7237.0
## - industry:south         1    755862 92062921 7237.9
## - weeks:gender           1    843241 92150300 7238.5
## - industry:union         1    904547 92211606 7238.9
## - south:education        1   1180683 92487742 7240.6
## - union:education        1   1319487 92626546 7241.5
## - weeks:married          1   1514222 92821281 7242.8
## 
## Step:  AIC=7233
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + south:ethnicity + smsa:married + smsa:gender + 
##     smsa:union + smsa:education + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:education + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:ethnicity        1       894 91308609 7231.0
## - south:union            1      1100 91308815 7231.0
## - experience:industry    1      1131 91308845 7231.0
## - smsa:education         1      1302 91309017 7231.0
## - gender:education       1      1747 91309461 7231.0
## - experience:south       1      2243 91309958 7231.0
## - weeks:union            1      3477 91311191 7231.0
## - occupation:south       1      3543 91311257 7231.0
## - smsa:married           1      7559 91315274 7231.1
## - weeks:industry         1      8188 91315903 7231.1
## - occupation:smsa        1      8340 91316054 7231.1
## - south:married          1     10496 91318211 7231.1
## - experience:smsa        1     13368 91321082 7231.1
## - occupation:gender      1     16780 91324494 7231.1
## - married:gender         1     19004 91326719 7231.1
## - smsa:ethnicity         1     20751 91328465 7231.1
## - south:gender           1     21158 91328872 7231.1
## - weeks:education        1     25791 91333505 7231.2
## - industry:married       1     26940 91334654 7231.2
## - occupation:ethnicity   1     44209 91351924 7231.3
## - education:ethnicity    1     45216 91352931 7231.3
## - occupation:married     1     60251 91367966 7231.4
## - south:smsa             1     64518 91372232 7231.4
## - industry:gender        1     65577 91373291 7231.4
## - weeks:ethnicity        1     67968 91375683 7231.4
## - union:ethnicity        1     77438 91385153 7231.5
## - gender:union           1     79225 91386939 7231.5
## - experience:married     1     89676 91397391 7231.6
## - weeks:occupation       1    101939 91409653 7231.7
## - experience:union       1    102977 91410692 7231.7
## - weeks:south            1    108557 91416272 7231.7
## - experience:gender      1    128598 91436312 7231.8
## - industry:education     1    143217 91450931 7231.9
## - smsa:gender            1    144843 91452557 7231.9
## - experience:ethnicity   1    152497 91460211 7232.0
## - weeks:smsa             1    156504 91464219 7232.0
## - married:union          1    189990 91497704 7232.2
## - industry:ethnicity     1    203710 91511424 7232.3
## - married:ethnicity      1    237397 91545111 7232.5
## - experience:weeks       1    243623 91551337 7232.6
## - smsa:union             1    248743 91556458 7232.6
## <none>                               91307714 7233.0
## - industry:smsa          1    397791 91705505 7233.6
## - experience:occupation  1    412653 91720368 7233.7
## - occupation:union       1    426855 91734570 7233.8
## - occupation:education   1    621645 91929359 7235.0
## - gender:ethnicity       1    626490 91934205 7235.1
## - industry:south         1    758603 92066317 7235.9
## - weeks:gender           1    842590 92150305 7236.5
## - industry:union         1   1034938 92342652 7237.7
## - south:education        1   1181633 92489348 7238.7
## - union:education        1   1332643 92640357 7239.6
## - weeks:married          1   1513613 92821327 7240.8
## 
## Step:  AIC=7231.01
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + smsa:married + smsa:gender + smsa:union + 
##     smsa:education + smsa:ethnicity + married:gender + married:union + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:union            1      1105 91309714 7229.0
## - experience:industry    1      1117 91309726 7229.0
## - smsa:education         1      1252 91309861 7229.0
## - gender:education       1      1727 91310335 7229.0
## - experience:south       1      2552 91311161 7229.0
## - weeks:union            1      3354 91311963 7229.0
## - occupation:south       1      3740 91312349 7229.0
## - smsa:married           1      7467 91316076 7229.1
## - weeks:industry         1      7787 91316396 7229.1
## - occupation:smsa        1      8195 91316804 7229.1
## - south:married          1     10035 91318644 7229.1
## - experience:smsa        1     13158 91321767 7229.1
## - occupation:gender      1     16014 91324622 7229.1
## - married:gender         1     19165 91327774 7229.1
## - south:gender           1     22202 91330811 7229.2
## - smsa:ethnicity         1     22937 91331546 7229.2
## - industry:married       1     26432 91335041 7229.2
## - weeks:education        1     27066 91335675 7229.2
## - occupation:ethnicity   1     45927 91354535 7229.3
## - education:ethnicity    1     46242 91354851 7229.3
## - occupation:married     1     59706 91368315 7229.4
## - industry:gender        1     66906 91375515 7229.4
## - weeks:ethnicity        1     69598 91378207 7229.5
## - south:smsa             1     72426 91381035 7229.5
## - gender:union           1     78677 91387286 7229.5
## - union:ethnicity        1     89603 91398212 7229.6
## - experience:married     1     90060 91398668 7229.6
## - weeks:occupation       1    101177 91409786 7229.7
## - experience:union       1    102250 91410859 7229.7
## - weeks:south            1    107679 91416288 7229.7
## - experience:gender      1    128151 91436760 7229.8
## - industry:education     1    144749 91453358 7230.0
## - smsa:gender            1    146220 91454828 7230.0
## - weeks:smsa             1    156815 91465423 7230.0
## - experience:ethnicity   1    162705 91471314 7230.1
## - married:union          1    192822 91501431 7230.3
## - industry:ethnicity     1    204624 91513233 7230.3
## - experience:weeks       1    243385 91551994 7230.6
## - smsa:union             1    248153 91556762 7230.6
## - married:ethnicity      1    255771 91564380 7230.7
## <none>                               91308609 7231.0
## - industry:smsa          1    400501 91709110 7231.6
## - experience:occupation  1    411762 91720371 7231.7
## - occupation:union       1    437048 91745657 7231.9
## - occupation:education   1    623737 91932346 7233.1
## - gender:ethnicity       1    634497 91943106 7233.1
## - industry:south         1    758484 92067092 7233.9
## - weeks:gender           1    896795 92205403 7234.8
## - industry:union         1   1034530 92343138 7235.7
## - south:education        1   1182880 92491489 7236.7
## - union:education        1   1332718 92641327 7237.6
## - weeks:married          1   1570636 92879244 7239.2
## 
## Step:  AIC=7229.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:industry    1      1087 91310801 7227.0
## - smsa:education         1      1422 91311135 7227.0
## - gender:education       1      1727 91311440 7227.0
## - experience:south       1      2304 91312018 7227.0
## - weeks:union            1      3183 91312897 7227.0
## - occupation:south       1      5314 91315028 7227.1
## - occupation:smsa        1      7325 91317038 7227.1
## - weeks:industry         1      7561 91317274 7227.1
## - smsa:married           1      7616 91317330 7227.1
## - south:married          1     10679 91320393 7227.1
## - experience:smsa        1     13141 91322854 7227.1
## - occupation:gender      1     15627 91325340 7227.1
## - married:gender         1     18935 91328649 7227.1
## - south:gender           1     21354 91331067 7227.2
## - smsa:ethnicity         1     22401 91332115 7227.2
## - industry:married       1     25952 91335665 7227.2
## - weeks:education        1     27745 91337458 7227.2
## - education:ethnicity    1     47106 91356819 7227.3
## - occupation:ethnicity   1     48537 91358251 7227.3
## - occupation:married     1     59072 91368786 7227.4
## - industry:gender        1     66784 91376498 7227.5
## - weeks:ethnicity        1     70281 91379994 7227.5
## - south:smsa             1     74168 91383881 7227.5
## - gender:union           1     77574 91387288 7227.5
## - union:ethnicity        1     88632 91398345 7227.6
## - experience:married     1     92173 91401886 7227.6
## - weeks:occupation       1    100385 91410098 7227.7
## - experience:union       1    101329 91411043 7227.7
## - weeks:south            1    107123 91416836 7227.7
## - experience:gender      1    128486 91438199 7227.9
## - industry:education     1    143665 91453378 7228.0
## - smsa:gender            1    146103 91455816 7228.0
## - weeks:smsa             1    158735 91468448 7228.1
## - experience:ethnicity   1    162464 91472178 7228.1
## - married:union          1    192607 91502321 7228.3
## - industry:ethnicity     1    204550 91514263 7228.3
## - experience:weeks       1    243451 91553164 7228.6
## - smsa:union             1    252834 91562548 7228.7
## - married:ethnicity      1    258376 91568089 7228.7
## <none>                               91309714 7229.0
## - industry:smsa          1    407013 91716727 7229.7
## - experience:occupation  1    422158 91731872 7229.8
## - occupation:union       1    447226 91756939 7229.9
## - occupation:education   1    630284 91939997 7231.1
## - gender:ethnicity       1    634198 91943911 7231.1
## - industry:south         1    766957 92076671 7232.0
## - weeks:gender           1    898271 92207985 7232.8
## - industry:union         1   1033427 92343140 7233.7
## - south:education        1   1190365 92500078 7234.7
## - union:education        1   1380414 92690128 7235.9
## - weeks:married          1   1570625 92880339 7237.2
## 
## Step:  AIC=7227.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:education         1      1342 91312143 7225.0
## - gender:education       1      1666 91312467 7225.0
## - experience:south       1      1838 91312638 7225.0
## - weeks:union            1      3087 91313888 7225.0
## - occupation:south       1      5086 91315886 7225.1
## - weeks:industry         1      7030 91317830 7225.1
## - smsa:married           1      7557 91318358 7225.1
## - occupation:smsa        1      7717 91318518 7225.1
## - south:married          1     11108 91321909 7225.1
## - experience:smsa        1     13292 91324093 7225.1
## - occupation:gender      1     15599 91326400 7225.1
## - married:gender         1     19115 91329915 7225.1
## - south:gender           1     21809 91332609 7225.2
## - smsa:ethnicity         1     22234 91333034 7225.2
## - industry:married       1     25124 91335925 7225.2
## - weeks:education        1     27583 91338384 7225.2
## - education:ethnicity    1     47495 91358296 7225.3
## - occupation:ethnicity   1     48161 91358961 7225.3
## - occupation:married     1     60106 91370907 7225.4
## - industry:gender        1     66629 91377429 7225.5
## - weeks:ethnicity        1     69830 91380631 7225.5
## - south:smsa             1     74029 91384830 7225.5
## - gender:union           1     78783 91389583 7225.5
## - union:ethnicity        1     87983 91398784 7225.6
## - experience:married     1     92371 91403171 7225.6
## - weeks:occupation       1    101606 91412407 7225.7
## - experience:union       1    102933 91413734 7225.7
## - weeks:south            1    106514 91417314 7225.7
## - experience:gender      1    127800 91438600 7225.9
## - smsa:gender            1    146555 91457356 7226.0
## - industry:education     1    158263 91469064 7226.1
## - weeks:smsa             1    159069 91469869 7226.1
## - experience:ethnicity   1    161453 91472253 7226.1
## - married:union          1    194039 91504839 7226.3
## - industry:ethnicity     1    204282 91515082 7226.4
## - experience:weeks       1    242367 91553167 7226.6
## - smsa:union             1    251810 91562611 7226.7
## - married:ethnicity      1    260542 91571342 7226.7
## <none>                               91310801 7227.0
## - industry:smsa          1    421468 91732269 7227.8
## - experience:occupation  1    436887 91747688 7227.9
## - occupation:union       1    446139 91756939 7227.9
## - occupation:education   1    629812 91940613 7229.1
## - gender:ethnicity       1    636293 91947094 7229.2
## - industry:south         1    768557 92079357 7230.0
## - weeks:gender           1    898368 92209169 7230.9
## - industry:union         1   1037784 92348585 7231.7
## - south:education        1   1189279 92500079 7232.7
## - union:education        1   1385837 92696637 7234.0
## - weeks:married          1   1572634 92883435 7235.2
## 
## Step:  AIC=7225.03
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:south       1      1717 91313860 7223.0
## - gender:education       1      1905 91314048 7223.0
## - weeks:union            1      3051 91315194 7223.1
## - occupation:south       1      4334 91316477 7223.1
## - weeks:industry         1      7045 91319187 7223.1
## - smsa:married           1      7313 91319455 7223.1
## - south:married          1     11262 91323404 7223.1
## - occupation:gender      1     15426 91327569 7223.1
## - experience:smsa        1     16694 91328837 7223.1
## - occupation:smsa        1     17469 91329612 7223.1
## - married:gender         1     18927 91331070 7223.2
## - smsa:ethnicity         1     21150 91333292 7223.2
## - south:gender           1     21720 91333863 7223.2
## - industry:married       1     24906 91337049 7223.2
## - weeks:education        1     27314 91339457 7223.2
## - occupation:ethnicity   1     47067 91359210 7223.3
## - education:ethnicity    1     53868 91366011 7223.4
## - occupation:married     1     60788 91372931 7223.4
## - industry:gender        1     66322 91378465 7223.5
## - weeks:ethnicity        1     69706 91381849 7223.5
## - south:smsa             1     72725 91384868 7223.5
## - gender:union           1     77765 91389908 7223.5
## - union:ethnicity        1     87305 91399448 7223.6
## - experience:married     1     91564 91403707 7223.6
## - weeks:occupation       1    101710 91413853 7223.7
## - experience:union       1    103284 91415427 7223.7
## - weeks:south            1    105397 91417540 7223.7
## - experience:gender      1    127824 91439967 7223.9
## - smsa:gender            1    145532 91457675 7224.0
## - industry:education     1    157406 91469549 7224.1
## - weeks:smsa             1    157727 91469870 7224.1
## - experience:ethnicity   1    163042 91475185 7224.1
## - married:union          1    193490 91505633 7224.3
## - industry:ethnicity     1    204054 91516197 7224.4
## - experience:weeks       1    242817 91554960 7224.6
## - smsa:union             1    250961 91563104 7224.7
## - married:ethnicity      1    262066 91574209 7224.7
## <none>                               91312143 7225.0
## - industry:smsa          1    423467 91735609 7225.8
## - experience:occupation  1    435581 91747724 7225.9
## - occupation:union       1    444852 91756995 7225.9
## - gender:ethnicity       1    636551 91948694 7227.2
## - occupation:education   1    652919 91965062 7227.3
## - industry:south         1    776195 92088338 7228.1
## - weeks:gender           1    897093 92209236 7228.9
## - industry:union         1   1036806 92348949 7229.8
## - south:education        1   1239977 92552120 7231.1
## - union:education        1   1397651 92709794 7232.1
## - weeks:married          1   1571293 92883435 7233.2
## 
## Step:  AIC=7223.04
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:education       1      1745 91315605 7221.1
## - weeks:union            1      2552 91316412 7221.1
## - occupation:south       1      4081 91317941 7221.1
## - weeks:industry         1      7273 91321133 7221.1
## - smsa:married           1      7344 91321204 7221.1
## - south:married          1     12279 91326139 7221.1
## - occupation:gender      1     15768 91329628 7221.1
## - occupation:smsa        1     17485 91331344 7221.2
## - married:gender         1     17811 91331670 7221.2
## - experience:smsa        1     19356 91333216 7221.2
## - south:gender           1     21269 91335128 7221.2
## - smsa:ethnicity         1     21986 91335846 7221.2
## - industry:married       1     24403 91338263 7221.2
## - weeks:education        1     28395 91342254 7221.2
## - occupation:ethnicity   1     46884 91360744 7221.4
## - education:ethnicity    1     55145 91369005 7221.4
## - occupation:married     1     62542 91376402 7221.5
## - industry:gender        1     65614 91379473 7221.5
## - weeks:ethnicity        1     69275 91383135 7221.5
## - south:smsa             1     74376 91388236 7221.5
## - gender:union           1     78727 91392587 7221.6
## - experience:married     1     90246 91404106 7221.6
## - union:ethnicity        1     91101 91404961 7221.6
## - weeks:occupation       1    101362 91415222 7221.7
## - experience:union       1    102218 91416078 7221.7
## - weeks:south            1    104300 91418160 7221.7
## - experience:gender      1    126269 91440129 7221.9
## - smsa:gender            1    145837 91459697 7222.0
## - industry:education     1    156397 91470257 7222.1
## - weeks:smsa             1    157214 91471074 7222.1
## - experience:ethnicity   1    179239 91493099 7222.2
## - married:union          1    199058 91512918 7222.3
## - industry:ethnicity     1    204337 91518197 7222.4
## - experience:weeks       1    241536 91555396 7222.6
## - smsa:union             1    252694 91566554 7222.7
## - married:ethnicity      1    261860 91575719 7222.7
## <none>                               91313860 7223.0
## - industry:smsa          1    423650 91737509 7223.8
## - experience:occupation  1    440113 91753972 7223.9
## - occupation:union       1    445680 91759540 7223.9
## - gender:ethnicity       1    638664 91952524 7225.2
## - occupation:education   1    655286 91969146 7225.3
## - industry:south         1    775025 92088885 7226.1
## - weeks:gender           1    895377 92209236 7226.9
## - industry:union         1   1035201 92349061 7227.8
## - south:education        1   1304488 92618348 7229.5
## - union:education        1   1403408 92717268 7230.1
## - weeks:married          1   1571747 92885606 7231.2
## 
## Step:  AIC=7221.06
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:union            1      2668 91318272 7219.1
## - occupation:south       1      4367 91319972 7219.1
## - weeks:industry         1      6825 91322429 7219.1
## - smsa:married           1      7490 91323095 7219.1
## - south:married          1     12573 91328178 7219.1
## - married:gender         1     16938 91332542 7219.2
## - occupation:smsa        1     16950 91332555 7219.2
## - experience:smsa        1     19484 91335088 7219.2
## - smsa:ethnicity         1     21367 91336972 7219.2
## - south:gender           1     21664 91337269 7219.2
## - occupation:gender      1     24385 91339990 7219.2
## - industry:married       1     24408 91340012 7219.2
## - weeks:education        1     30894 91346498 7219.3
## - occupation:ethnicity   1     45308 91360913 7219.4
## - education:ethnicity    1     59815 91375420 7219.4
## - occupation:married     1     62958 91378563 7219.5
## - industry:gender        1     64608 91380213 7219.5
## - weeks:ethnicity        1     69280 91384884 7219.5
## - south:smsa             1     74123 91389728 7219.5
## - gender:union           1     81714 91397318 7219.6
## - experience:married     1     90675 91406280 7219.6
## - union:ethnicity        1     91061 91406666 7219.6
## - weeks:occupation       1    100261 91415865 7219.7
## - experience:union       1    103019 91418623 7219.7
## - weeks:south            1    104522 91420126 7219.7
## - experience:gender      1    125629 91441233 7219.9
## - smsa:gender            1    148130 91463734 7220.0
## - weeks:smsa             1    156892 91472496 7220.1
## - industry:education     1    166052 91481657 7220.1
## - experience:ethnicity   1    181902 91497507 7220.2
## - married:union          1    199765 91515370 7220.4
## - industry:ethnicity     1    202699 91518303 7220.4
## - experience:weeks       1    247836 91563441 7220.7
## - smsa:union             1    250959 91566563 7220.7
## - married:ethnicity      1    272586 91588190 7220.8
## <none>                               91315605 7221.1
## - industry:smsa          1    425397 91741002 7221.8
## - experience:occupation  1    440749 91756353 7221.9
## - occupation:union       1    451247 91766851 7222.0
## - occupation:education   1    654644 91970249 7223.3
## - gender:ethnicity       1    668144 91983749 7223.4
## - industry:south         1    773281 92088886 7224.1
## - weeks:gender           1    897886 92213491 7224.9
## - industry:union         1   1034299 92349904 7225.8
## - south:education        1   1307257 92622861 7227.5
## - union:education        1   1402900 92718505 7228.1
## - weeks:married          1   1571155 92886760 7229.2
## 
## Step:  AIC=7219.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:south       1      3893 91322166 7217.1
## - weeks:industry         1      6916 91325189 7217.1
## - smsa:married           1      7675 91325947 7217.1
## - south:married          1     12776 91331048 7217.2
## - married:gender         1     17144 91335417 7217.2
## - experience:smsa        1     17755 91336028 7217.2
## - occupation:smsa        1     18227 91336499 7217.2
## - smsa:ethnicity         1     21099 91339371 7217.2
## - south:gender           1     21461 91339733 7217.2
## - occupation:gender      1     24316 91342588 7217.2
## - industry:married       1     25173 91343445 7217.2
## - weeks:education        1     32162 91350434 7217.3
## - occupation:ethnicity   1     45552 91363825 7217.4
## - education:ethnicity    1     59925 91378197 7217.5
## - industry:gender        1     64148 91382421 7217.5
## - occupation:married     1     64380 91382652 7217.5
## - weeks:ethnicity        1     74558 91392830 7217.6
## - south:smsa             1     75658 91393930 7217.6
## - gender:union           1     79966 91398238 7217.6
## - experience:married     1     90317 91408589 7217.7
## - union:ethnicity        1     90694 91408967 7217.7
## - experience:union       1    100497 91418770 7217.7
## - weeks:south            1    101897 91420169 7217.7
## - weeks:occupation       1    116904 91435176 7217.8
## - experience:gender      1    124392 91442664 7217.9
## - smsa:gender            1    148530 91466802 7218.0
## - industry:education     1    165536 91483808 7218.2
## - experience:ethnicity   1    181221 91499493 7218.3
## - weeks:smsa             1    200247 91518520 7218.4
## - industry:ethnicity     1    200951 91519223 7218.4
## - married:union          1    203103 91521376 7218.4
## - experience:weeks       1    245208 91563481 7218.7
## - smsa:union             1    271016 91589289 7218.8
## - married:ethnicity      1    273184 91591456 7218.9
## <none>                               91318272 7219.1
## - industry:smsa          1    422790 91741062 7219.8
## - experience:occupation  1    443420 91761692 7220.0
## - occupation:union       1    448761 91767034 7220.0
## - occupation:education   1    660097 91978370 7221.4
## - gender:ethnicity       1    667219 91985491 7221.4
## - industry:south         1    772424 92090696 7222.1
## - weeks:gender           1    900033 92218305 7222.9
## - industry:union         1   1033007 92351279 7223.8
## - south:education        1   1307956 92626228 7225.5
## - union:education        1   1408689 92726961 7226.2
## - weeks:married          1   1586335 92904608 7227.3
## 
## Step:  AIC=7217.1
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:married           1      7707 91329872 7215.1
## - weeks:industry         1      7809 91329974 7215.1
## - south:married          1     12580 91334746 7215.2
## - married:gender         1     17096 91339261 7215.2
## - experience:smsa        1     17273 91339439 7215.2
## - occupation:smsa        1     20465 91342631 7215.2
## - south:gender           1     20777 91342942 7215.2
## - smsa:ethnicity         1     22236 91344402 7215.2
## - occupation:gender      1     24075 91346241 7215.3
## - industry:married       1     24991 91347157 7215.3
## - weeks:education        1     33460 91355626 7215.3
## - occupation:ethnicity   1     42773 91364938 7215.4
## - education:ethnicity    1     60640 91382806 7215.5
## - occupation:married     1     63679 91385845 7215.5
## - industry:gender        1     63934 91386100 7215.5
## - south:smsa             1     72845 91395011 7215.6
## - weeks:ethnicity        1     77439 91399605 7215.6
## - gender:union           1     79870 91402036 7215.6
## - experience:married     1     89189 91411354 7215.7
## - union:ethnicity        1     95765 91417931 7215.7
## - experience:union       1    101071 91423237 7215.8
## - weeks:south            1    101856 91424022 7215.8
## - weeks:occupation       1    114285 91436450 7215.8
## - experience:gender      1    123614 91445779 7215.9
## - smsa:gender            1    149012 91471178 7216.1
## - industry:education     1    162028 91484194 7216.2
## - experience:ethnicity   1    180620 91502786 7216.3
## - weeks:smsa             1    200350 91522515 7216.4
## - married:union          1    202554 91524720 7216.4
## - industry:ethnicity     1    204837 91527003 7216.4
## - experience:weeks       1    243664 91565830 7216.7
## - married:ethnicity      1    269662 91591827 7216.9
## - smsa:union             1    282666 91604831 7216.9
## <none>                               91322166 7217.1
## - industry:smsa          1    424610 91746776 7217.9
## - experience:occupation  1    442474 91764640 7218.0
## - occupation:union       1    473189 91795355 7218.2
## - occupation:education   1    657721 91979886 7219.4
## - gender:ethnicity       1    664937 91987103 7219.4
## - industry:south         1    810849 92133015 7220.4
## - weeks:gender           1    898963 92221129 7220.9
## - industry:union         1   1041789 92363954 7221.8
## - union:education        1   1413780 92735945 7224.2
## - weeks:married          1   1586977 92909143 7225.3
## - south:education        1   1743189 93065355 7226.3
## 
## Step:  AIC=7215.15
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:industry         1      6887 91336760 7213.2
## - south:married          1     16580 91346452 7213.3
## - occupation:smsa        1     19084 91348957 7213.3
## - married:gender         1     19348 91349220 7213.3
## - experience:smsa        1     19445 91349317 7213.3
## - occupation:gender      1     20812 91350684 7213.3
## - industry:married       1     21738 91351611 7213.3
## - smsa:ethnicity         1     23180 91353052 7213.3
## - south:gender           1     24786 91354659 7213.3
## - weeks:education        1     34402 91364275 7213.4
## - occupation:ethnicity   1     45208 91375080 7213.4
## - occupation:married     1     57552 91387424 7213.5
## - industry:gender        1     61581 91391454 7213.6
## - education:ethnicity    1     62296 91392168 7213.6
## - south:smsa             1     75320 91405193 7213.6
## - weeks:ethnicity        1     75641 91405513 7213.6
## - gender:union           1     78207 91408080 7213.7
## - experience:married     1     90993 91420865 7213.7
## - union:ethnicity        1     93786 91423658 7213.8
## - weeks:south            1     97734 91427607 7213.8
## - experience:union       1    101107 91430979 7213.8
## - weeks:occupation       1    115334 91445207 7213.9
## - experience:gender      1    125634 91455506 7214.0
## - industry:education     1    160208 91490081 7214.2
## - experience:ethnicity   1    182456 91512329 7214.3
## - weeks:smsa             1    196729 91526602 7214.4
## - married:union          1    199085 91528957 7214.4
## - industry:ethnicity     1    202175 91532047 7214.5
## - experience:weeks       1    240350 91570222 7214.7
## - smsa:union             1    277162 91607034 7215.0
## - married:ethnicity      1    280645 91610518 7215.0
## <none>                               91329872 7215.1
## - smsa:gender            1    334544 91664417 7215.3
## - industry:smsa          1    429397 91759269 7215.9
## - experience:occupation  1    441514 91771387 7216.0
## - occupation:union       1    474188 91804060 7216.2
## - occupation:education   1    661204 91991077 7217.4
## - gender:ethnicity       1    675499 92005371 7217.5
## - industry:south         1    835478 92165351 7218.6
## - weeks:gender           1    922055 92251927 7219.1
## - industry:union         1   1034239 92364112 7219.8
## - union:education        1   1420257 92750129 7222.3
## - weeks:married          1   1629901 92959773 7223.7
## - south:education        1   1740631 93070503 7224.4
## 
## Step:  AIC=7213.19
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:married          1     18218 91354977 7211.3
## - occupation:gender      1     19000 91355759 7211.3
## - experience:smsa        1     19446 91356206 7211.3
## - occupation:smsa        1     19826 91356585 7211.3
## - married:gender         1     20235 91356994 7211.3
## - smsa:ethnicity         1     21306 91358066 7211.3
## - industry:married       1     21721 91358480 7211.3
## - south:gender           1     25794 91362554 7211.4
## - weeks:education        1     43083 91379842 7211.5
## - occupation:ethnicity   1     47833 91384593 7211.5
## - occupation:married     1     58036 91394796 7211.6
## - education:ethnicity    1     61386 91398146 7211.6
## - industry:gender        1     66112 91402871 7211.6
## - south:smsa             1     75172 91411932 7211.7
## - gender:union           1     77329 91414089 7211.7
## - weeks:ethnicity        1     92263 91429022 7211.8
## - experience:married     1     93796 91430555 7211.8
## - union:ethnicity        1     94576 91431335 7211.8
## - experience:union       1    102818 91439578 7211.9
## - weeks:south            1    109013 91445772 7211.9
## - experience:gender      1    130727 91467487 7212.0
## - weeks:occupation       1    141885 91478644 7212.1
## - industry:education     1    160715 91497474 7212.2
## - experience:ethnicity   1    184771 91521530 7212.4
## - married:union          1    197558 91534318 7212.5
## - industry:ethnicity     1    199423 91536182 7212.5
## - weeks:smsa             1    239991 91576750 7212.8
## - experience:weeks       1    255997 91592757 7212.9
## - smsa:union             1    275402 91612162 7213.0
## - married:ethnicity      1    288277 91625037 7213.1
## <none>                               91336760 7213.2
## - smsa:gender            1    340671 91677431 7213.4
## - industry:smsa          1    434038 91770797 7214.0
## - experience:occupation  1    441980 91778740 7214.1
## - occupation:union       1    468187 91804946 7214.2
## - occupation:education   1    655228 91991988 7215.4
## - gender:ethnicity       1    688291 92025051 7215.7
## - industry:south         1    828621 92165381 7216.6
## - industry:union         1   1030914 92367673 7217.9
## - weeks:gender           1   1037751 92374511 7217.9
## - union:education        1   1425423 92762183 7220.4
## - weeks:married          1   1681076 93017835 7222.0
## - south:education        1   1737991 93074750 7222.4
## 
## Step:  AIC=7211.31
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:gender + 
##     south:education + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:gender           1      8466 91363443 7209.4
## - married:gender         1     14175 91369152 7209.4
## - occupation:smsa        1     17451 91372428 7209.4
## - occupation:gender      1     17785 91372762 7209.4
## - experience:smsa        1     21326 91376304 7209.5
## - industry:married       1     23414 91378392 7209.5
## - smsa:ethnicity         1     23464 91378441 7209.5
## - weeks:education        1     40262 91395239 7209.6
## - occupation:ethnicity   1     44127 91399104 7209.6
## - occupation:married     1     53796 91408773 7209.7
## - education:ethnicity    1     63419 91418397 7209.7
## - gender:union           1     65883 91420860 7209.7
## - industry:gender        1     67062 91422040 7209.7
## - south:smsa             1     68430 91423407 7209.8
## - union:ethnicity        1    100691 91455668 7210.0
## - weeks:ethnicity        1    104000 91458977 7210.0
## - experience:married     1    107638 91462615 7210.0
## - experience:union       1    111593 91466570 7210.0
## - weeks:south            1    119708 91474685 7210.1
## - experience:gender      1    144513 91499490 7210.3
## - weeks:occupation       1    151510 91506487 7210.3
## - industry:education     1    152457 91507434 7210.3
## - married:union          1    179368 91534346 7210.5
## - experience:ethnicity   1    186211 91541188 7210.5
## - industry:ethnicity     1    195886 91550864 7210.6
## - weeks:smsa             1    247851 91602828 7210.9
## - smsa:union             1    262745 91617722 7211.0
## - experience:weeks       1    265322 91620300 7211.0
## - married:ethnicity      1    270866 91625844 7211.1
## <none>                               91354977 7211.3
## - smsa:gender            1    336089 91691066 7211.5
## - industry:smsa          1    422427 91777404 7212.1
## - experience:occupation  1    433262 91788239 7212.1
## - occupation:union       1    466110 91821087 7212.3
## - occupation:education   1    664273 92019250 7213.6
## - gender:ethnicity       1    671907 92026885 7213.7
## - industry:south         1    836437 92191414 7214.7
## - weeks:gender           1   1032352 92387329 7216.0
## - industry:union         1   1037249 92392226 7216.0
## - union:education        1   1421036 92776014 7218.5
## - weeks:married          1   1691530 93046507 7220.2
## - south:education        1   1733563 93088540 7220.5
## 
## Step:  AIC=7209.37
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:gender         1     11110 91374554 7207.4
## - occupation:smsa        1     17997 91381441 7207.5
## - experience:smsa        1     20351 91383795 7207.5
## - occupation:gender      1     21238 91384681 7207.5
## - industry:married       1     23339 91386782 7207.5
## - smsa:ethnicity         1     23903 91387346 7207.5
## - weeks:education        1     39669 91403112 7207.6
## - occupation:ethnicity   1     44510 91407954 7207.7
## - occupation:married     1     55041 91418484 7207.7
## - gender:union           1     58337 91421780 7207.7
## - education:ethnicity    1     64554 91427998 7207.8
## - industry:gender        1     65162 91428605 7207.8
## - south:smsa             1     76986 91440430 7207.9
## - union:ethnicity        1    101496 91464939 7208.0
## - weeks:ethnicity        1    107353 91470797 7208.1
## - experience:union       1    109257 91472700 7208.1
## - experience:married     1    109660 91473103 7208.1
## - weeks:south            1    115876 91479319 7208.1
## - experience:gender      1    140512 91503955 7208.3
## - weeks:occupation       1    149829 91513273 7208.3
## - industry:education     1    158477 91521920 7208.4
## - married:union          1    180649 91544092 7208.5
## - experience:ethnicity   1    188171 91551615 7208.6
## - industry:ethnicity     1    199309 91562753 7208.7
## - weeks:smsa             1    249759 91613202 7209.0
## - married:ethnicity      1    266563 91630007 7209.1
## - experience:weeks       1    267124 91630567 7209.1
## - smsa:union             1    272171 91635614 7209.1
## <none>                               91363443 7209.4
## - smsa:gender            1    327972 91691415 7209.5
## - industry:smsa          1    421192 91784636 7210.1
## - experience:occupation  1    440106 91803549 7210.2
## - occupation:union       1    468761 91832204 7210.4
## - gender:ethnicity       1    668073 92031516 7211.7
## - occupation:education   1    671651 92035095 7211.7
## - industry:south         1    831462 92194905 7212.8
## - industry:union         1   1029584 92393027 7214.0
## - weeks:gender           1   1049011 92412455 7214.2
## - union:education        1   1414951 92778395 7216.5
## - weeks:married          1   1687582 93051025 7218.3
## - south:education        1   1725340 93088783 7218.5
## 
## Step:  AIC=7207.44
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:union + 
##     married:ethnicity + gender:union + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:gender      1     17190 91391744 7205.6
## - occupation:smsa        1     17689 91392243 7205.6
## - industry:married       1     19620 91394174 7205.6
## - experience:smsa        1     20354 91394908 7205.6
## - smsa:ethnicity         1     23061 91397614 7205.6
## - weeks:education        1     40111 91414665 7205.7
## - occupation:ethnicity   1     43199 91417753 7205.7
## - occupation:married     1     48815 91423369 7205.8
## - industry:gender        1     59503 91434057 7205.8
## - gender:union           1     59823 91434377 7205.8
## - education:ethnicity    1     65265 91439819 7205.9
## - south:smsa             1     76361 91450915 7205.9
## - experience:married     1    100486 91475040 7206.1
## - union:ethnicity        1    104255 91478809 7206.1
## - weeks:ethnicity        1    105962 91480516 7206.1
## - experience:union       1    108205 91482759 7206.1
## - weeks:south            1    115128 91489682 7206.2
## - experience:gender      1    129407 91503961 7206.3
## - weeks:occupation       1    151336 91525890 7206.4
## - industry:education     1    155555 91530109 7206.5
## - married:union          1    179892 91554446 7206.6
## - experience:ethnicity   1    199356 91573910 7206.7
## - industry:ethnicity     1    202324 91576878 7206.8
## - weeks:smsa             1    249640 91624194 7207.1
## - experience:weeks       1    263359 91637913 7207.2
## - married:ethnicity      1    267315 91641869 7207.2
## - smsa:union             1    271766 91646320 7207.2
## <none>                               91374554 7207.4
## - smsa:gender            1    326210 91700764 7207.6
## - industry:smsa          1    424659 91799212 7208.2
## - experience:occupation  1    445963 91820517 7208.3
## - occupation:union       1    473104 91847658 7208.5
## - gender:ethnicity       1    663953 92038506 7209.7
## - occupation:education   1    682836 92057390 7209.9
## - industry:south         1    838793 92213347 7210.9
## - industry:union         1   1036826 92411380 7212.2
## - weeks:gender           1   1095032 92469586 7212.5
## - union:education        1   1411066 92785620 7214.6
## - south:education        1   1714230 93088783 7216.5
## - weeks:married          1   1719115 93093669 7216.5
## 
## Step:  AIC=7205.55
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:smsa        1     17000 91408745 7203.7
## - smsa:ethnicity         1     18606 91410350 7203.7
## - experience:smsa        1     18609 91410353 7203.7
## - industry:married       1     19694 91411438 7203.7
## - occupation:married     1     31806 91423550 7203.8
## - weeks:education        1     40415 91432159 7203.8
## - occupation:ethnicity   1     45014 91436758 7203.8
## - gender:union           1     49392 91441136 7203.9
## - education:ethnicity    1     64206 91455951 7204.0
## - south:smsa             1     75165 91466909 7204.0
## - industry:gender        1     79296 91471040 7204.1
## - experience:married     1     98478 91490222 7204.2
## - union:ethnicity        1    108195 91499939 7204.3
## - weeks:south            1    115300 91507044 7204.3
## - experience:union       1    116056 91507800 7204.3
## - weeks:ethnicity        1    116394 91508138 7204.3
## - experience:gender      1    125855 91517600 7204.4
## - industry:education     1    158734 91550478 7204.6
## - weeks:occupation       1    159956 91551700 7204.6
## - married:union          1    162706 91554450 7204.6
## - industry:ethnicity     1    196886 91588631 7204.8
## - experience:ethnicity   1    197896 91589640 7204.8
## - married:ethnicity      1    259522 91651267 7205.2
## - weeks:smsa             1    262559 91654303 7205.3
## - experience:weeks       1    262864 91654608 7205.3
## - smsa:union             1    269943 91661687 7205.3
## <none>                               91391744 7205.6
## - smsa:gender            1    395113 91786858 7206.1
## - industry:smsa          1    428208 91819952 7206.3
## - experience:occupation  1    440361 91832105 7206.4
## - occupation:union       1    461644 91853388 7206.5
## - occupation:education   1    688566 92080311 7208.0
## - gender:ethnicity       1    712771 92104515 7208.2
## - industry:south         1    831919 92223663 7208.9
## - industry:union         1   1069249 92460994 7210.5
## - weeks:gender           1   1183895 92575639 7211.2
## - union:education        1   1453311 92845055 7212.9
## - south:education        1   1702427 93094171 7214.5
## - weeks:married          1   1841478 93233222 7215.4
## 
## Step:  AIC=7203.66
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:ethnicity         1     17922 91426666 7201.8
## - industry:married       1     21311 91430055 7201.8
## - experience:smsa        1     21327 91430071 7201.8
## - occupation:married     1     26826 91435571 7201.8
## - weeks:education        1     40725 91449469 7201.9
## - occupation:ethnicity   1     47176 91455920 7202.0
## - gender:union           1     48037 91456782 7202.0
## - education:ethnicity    1     65247 91473991 7202.1
## - south:smsa             1     70116 91478861 7202.1
## - industry:gender        1     81317 91490061 7202.2
## - experience:married     1     95534 91504278 7202.3
## - union:ethnicity        1    109629 91518374 7202.4
## - weeks:south            1    114801 91523545 7202.4
## - weeks:ethnicity        1    116168 91524913 7202.4
## - experience:gender      1    126024 91534769 7202.5
## - experience:union       1    129849 91538593 7202.5
## - industry:education     1    147294 91556038 7202.6
## - married:union          1    156034 91564779 7202.7
## - weeks:occupation       1    156638 91565383 7202.7
## - industry:ethnicity     1    197375 91606120 7202.9
## - experience:ethnicity   1    204894 91613638 7203.0
## - weeks:smsa             1    254546 91663291 7203.3
## - smsa:union             1    258736 91667480 7203.3
## - experience:weeks       1    260946 91669690 7203.4
## - married:ethnicity      1    271129 91679874 7203.4
## <none>                               91408745 7203.7
## - smsa:gender            1    391182 91799926 7204.2
## - industry:smsa          1    411218 91819962 7204.3
## - experience:occupation  1    424247 91832991 7204.4
## - occupation:union       1    501696 91910441 7204.9
## - occupation:education   1    671830 92080574 7206.0
## - gender:ethnicity       1    751230 92159975 7206.5
## - industry:south         1    833714 92242458 7207.1
## - industry:union         1   1127234 92535978 7209.0
## - weeks:gender           1   1177229 92585974 7209.3
## - union:education        1   1471572 92880316 7211.2
## - south:education        1   1691432 93100177 7212.6
## - weeks:married          1   1841985 93250730 7213.5
## 
## Step:  AIC=7201.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:married       1     21330 91447997 7199.9
## - experience:smsa        1     23495 91450161 7199.9
## - occupation:married     1     24115 91450782 7199.9
## - weeks:education        1     40137 91466804 7200.0
## - gender:union           1     43186 91469852 7200.1
## - occupation:ethnicity   1     57533 91484199 7200.2
## - south:smsa             1     81667 91508333 7200.3
## - industry:gender        1     82997 91509663 7200.3
## - education:ethnicity    1     90616 91517282 7200.4
## - experience:married     1     93930 91520596 7200.4
## - union:ethnicity        1     96936 91523602 7200.4
## - weeks:ethnicity        1    114677 91541343 7200.5
## - weeks:south            1    115965 91542632 7200.5
## - experience:gender      1    121506 91548173 7200.6
## - experience:union       1    126869 91553535 7200.6
## - married:union          1    151534 91578200 7200.8
## - industry:education     1    157328 91583994 7200.8
## - weeks:occupation       1    162502 91589168 7200.8
## - industry:ethnicity     1    190598 91617264 7201.0
## - experience:ethnicity   1    222831 91649497 7201.2
## - weeks:smsa             1    252389 91679056 7201.4
## - experience:weeks       1    260498 91687164 7201.5
## - smsa:union             1    263873 91690539 7201.5
## - married:ethnicity      1    276656 91703322 7201.6
## <none>                               91426666 7201.8
## - smsa:gender            1    382927 91809593 7202.3
## - industry:smsa          1    416465 91843131 7202.5
## - experience:occupation  1    418286 91844952 7202.5
## - occupation:union       1    493523 91920189 7203.0
## - occupation:education   1    671017 92097683 7204.1
## - gender:ethnicity       1    744522 92171188 7204.6
## - industry:south         1    849931 92276598 7205.3
## - industry:union         1   1113062 92539729 7207.0
## - weeks:gender           1   1201990 92628656 7207.6
## - union:education        1   1468439 92895105 7209.3
## - south:education        1   1705058 93131725 7210.8
## - weeks:married          1   1878944 93305610 7211.9
## 
## Step:  AIC=7199.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:smsa        1     24165 91472162 7198.1
## - occupation:married     1     25409 91473406 7198.1
## - gender:union           1     36054 91484050 7198.2
## - weeks:education        1     46726 91494723 7198.2
## - occupation:ethnicity   1     58581 91506577 7198.3
## - industry:gender        1     62378 91510374 7198.3
## - experience:married     1     83440 91531436 7198.5
## - south:smsa             1     89891 91537888 7198.5
## - education:ethnicity    1     93833 91541830 7198.5
## - weeks:south            1    107662 91555658 7198.6
## - union:ethnicity        1    108123 91556119 7198.6
## - weeks:ethnicity        1    112078 91560074 7198.6
## - experience:gender      1    114597 91562594 7198.7
## - experience:union       1    128856 91576852 7198.8
## - married:union          1    134849 91582846 7198.8
## - industry:education     1    156138 91604135 7198.9
## - weeks:occupation       1    157658 91605654 7198.9
## - industry:ethnicity     1    181886 91629882 7199.1
## - experience:ethnicity   1    228589 91676585 7199.4
## - weeks:smsa             1    246640 91694637 7199.5
## - experience:weeks       1    252860 91700856 7199.6
## - smsa:union             1    255258 91703254 7199.6
## - married:ethnicity      1    267567 91715564 7199.7
## <none>                               91447997 7199.9
## - smsa:gender            1    385844 91833841 7200.4
## - experience:occupation  1    412439 91860436 7200.6
## - industry:smsa          1    438254 91886251 7200.8
## - occupation:union       1    488114 91936111 7201.1
## - occupation:education   1    658867 92106864 7202.2
## - gender:ethnicity       1    735763 92183759 7202.7
## - industry:south         1    855705 92303701 7203.5
## - industry:union         1   1099695 92547692 7205.0
## - weeks:gender           1   1216197 92664194 7205.8
## - union:education        1   1465201 92913197 7207.4
## - south:education        1   1690266 93138262 7208.8
## - weeks:married          1   1911054 93359051 7210.2
## 
## Step:  AIC=7198.08
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:married     1     27214 91499376 7196.3
## - gender:union           1     36173 91508335 7196.3
## - weeks:education        1     47415 91519577 7196.4
## - occupation:ethnicity   1     58633 91530795 7196.5
## - industry:gender        1     60377 91532539 7196.5
## - experience:married     1     89620 91561782 7196.7
## - south:smsa             1     92373 91564535 7196.7
## - education:ethnicity    1     95426 91567588 7196.7
## - union:ethnicity        1    104033 91576195 7196.8
## - experience:gender      1    107012 91579174 7196.8
## - weeks:south            1    107629 91579791 7196.8
## - weeks:ethnicity        1    113805 91585967 7196.8
## - experience:union       1    118126 91590287 7196.8
## - married:union          1    134116 91606278 7196.9
## - industry:education     1    150156 91622317 7197.1
## - weeks:occupation       1    153588 91625750 7197.1
## - industry:ethnicity     1    179847 91652008 7197.2
## - experience:ethnicity   1    218699 91690860 7197.5
## - experience:weeks       1    241028 91713189 7197.6
## - weeks:smsa             1    260665 91732826 7197.8
## - married:ethnicity      1    263929 91736090 7197.8
## - smsa:union             1    266964 91739126 7197.8
## <none>                               91472162 7198.1
## - industry:smsa          1    423052 91895214 7198.8
## - smsa:gender            1    435613 91907775 7198.9
## - experience:occupation  1    462201 91934363 7199.1
## - occupation:union       1    483054 91955215 7199.2
## - occupation:education   1    655183 92127344 7200.3
## - gender:ethnicity       1    728809 92200971 7200.8
## - industry:south         1    866006 92338168 7201.7
## - industry:union         1   1126718 92598879 7203.4
## - weeks:gender           1   1230469 92702630 7204.0
## - union:education        1   1461939 92934101 7205.5
## - south:education        1   1668715 93140876 7206.8
## - weeks:married          1   1915526 93387688 7208.4
## 
## Step:  AIC=7196.25
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:union           1     24521 91523897 7194.4
## - industry:gender        1     42492 91541868 7194.5
## - occupation:ethnicity   1     45483 91544859 7194.5
## - weeks:education        1     46152 91545528 7194.6
## - experience:married     1     81562 91580938 7194.8
## - south:smsa             1     91839 91591215 7194.8
## - education:ethnicity    1     95964 91595340 7194.9
## - experience:gender      1    106367 91605743 7194.9
## - married:union          1    108704 91608080 7195.0
## - weeks:south            1    111022 91610398 7195.0
## - union:ethnicity        1    116632 91616007 7195.0
## - weeks:ethnicity        1    121637 91621013 7195.0
## - experience:union       1    121697 91621073 7195.0
## - industry:education     1    144126 91643502 7195.2
## - weeks:occupation       1    150637 91650013 7195.2
## - industry:ethnicity     1    194053 91693429 7195.5
## - experience:ethnicity   1    219638 91719014 7195.7
## - experience:weeks       1    251198 91750574 7195.9
## - married:ethnicity      1    255197 91754573 7195.9
## - smsa:union             1    261403 91760778 7195.9
## - weeks:smsa             1    262530 91761906 7196.0
## <none>                               91499376 7196.3
## - smsa:gender            1    408406 91907782 7196.9
## - industry:smsa          1    418526 91917902 7197.0
## - experience:occupation  1    436101 91935477 7197.1
## - occupation:union       1    521804 92021180 7197.6
## - occupation:education   1    641790 92141165 7198.4
## - gender:ethnicity       1    702233 92201609 7198.8
## - industry:south         1    878094 92377470 7199.9
## - industry:union         1   1142034 92641410 7201.6
## - weeks:gender           1   1251927 92751303 7202.3
## - union:education        1   1448332 92947708 7203.6
## - south:education        1   1669678 93169054 7205.0
## - weeks:married          1   2039461 93538837 7207.4
## 
## Step:  AIC=7194.41
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:gender        1     36721 91560617 7192.7
## - weeks:education        1     41723 91565619 7192.7
## - occupation:ethnicity   1     42898 91566794 7192.7
## - experience:married     1     83163 91607059 7193.0
## - south:smsa             1     84850 91608747 7193.0
## - married:union          1     88831 91612728 7193.0
## - education:ethnicity    1    100274 91624171 7193.1
## - experience:gender      1    108851 91632748 7193.1
## - union:ethnicity        1    116030 91639926 7193.2
## - weeks:south            1    119829 91643726 7193.2
## - weeks:ethnicity        1    123414 91647311 7193.2
## - experience:union       1    132488 91656385 7193.3
## - industry:education     1    134493 91658390 7193.3
## - weeks:occupation       1    157170 91681067 7193.4
## - industry:ethnicity     1    182444 91706341 7193.6
## - experience:ethnicity   1    233535 91757432 7193.9
## - experience:weeks       1    250494 91774391 7194.0
## - married:ethnicity      1    251663 91775559 7194.0
## - smsa:union             1    263067 91786963 7194.1
## - weeks:smsa             1    268040 91791937 7194.2
## <none>                               91523897 7194.4
## - smsa:gender            1    422425 91946322 7195.2
## - industry:smsa          1    422686 91946583 7195.2
## - experience:occupation  1    428356 91952253 7195.2
## - occupation:union       1    528811 92052707 7195.8
## - occupation:education   1    630567 92154463 7196.5
## - gender:ethnicity       1    697487 92221384 7196.9
## - industry:south         1    887674 92411570 7198.2
## - industry:union         1   1146934 92670831 7199.8
## - weeks:gender           1   1281983 92805880 7200.7
## - union:education        1   1491022 93014919 7202.0
## - south:education        1   1671819 93195716 7203.2
## - weeks:married          1   2026020 93549916 7205.4
## 
## Step:  AIC=7192.65
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:education        1     43059 91603677 7190.9
## - occupation:ethnicity   1     45270 91605887 7190.9
## - education:ethnicity    1     82150 91642767 7191.2
## - experience:married     1     82402 91643020 7191.2
## - south:smsa             1     86945 91647563 7191.2
## - experience:gender      1     91359 91651976 7191.2
## - married:union          1    100244 91660862 7191.3
## - union:ethnicity        1    117665 91678282 7191.4
## - experience:union       1    121657 91682274 7191.4
## - weeks:ethnicity        1    122983 91683600 7191.4
## - industry:education     1    126738 91687355 7191.5
## - weeks:south            1    127391 91688009 7191.5
## - weeks:occupation       1    160971 91721588 7191.7
## - experience:weeks       1    239281 91799899 7192.2
## - married:ethnicity      1    242734 91803351 7192.2
## - experience:ethnicity   1    242879 91803496 7192.2
## - industry:ethnicity     1    253952 91814569 7192.3
## - weeks:smsa             1    268091 91828708 7192.4
## - smsa:union             1    276719 91837336 7192.4
## <none>                               91560617 7192.7
## - industry:smsa          1    406681 91967298 7193.3
## - smsa:gender            1    430952 91991570 7193.4
## - experience:occupation  1    438906 91999523 7193.5
## - occupation:union       1    525486 92086103 7194.1
## - occupation:education   1    639533 92200150 7194.8
## - gender:ethnicity       1    708776 92269393 7195.2
## - industry:south         1    895404 92456021 7196.4
## - industry:union         1   1188027 92748644 7198.3
## - weeks:gender           1   1350715 92911332 7199.4
## - union:education        1   1464888 93025505 7200.1
## - south:education        1   1685709 93246326 7201.5
## - weeks:married          1   2063089 93623706 7203.9
## 
## Step:  AIC=7190.93
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:ethnicity   1     42650 91646326 7189.2
## - experience:married     1     79377 91683054 7189.4
## - experience:gender      1     80236 91683912 7189.5
## - education:ethnicity    1     82696 91686373 7189.5
## - south:smsa             1     94496 91698172 7189.5
## - weeks:ethnicity        1    100938 91704615 7189.6
## - married:union          1    107272 91710949 7189.6
## - union:ethnicity        1    109104 91712780 7189.6
## - industry:education     1    120659 91724336 7189.7
## - experience:union       1    123666 91727343 7189.7
## - weeks:south            1    161510 91765187 7190.0
## - married:ethnicity      1    229487 91833164 7190.4
## - experience:ethnicity   1    240756 91844433 7190.5
## - industry:ethnicity     1    245801 91849478 7190.5
## - weeks:smsa             1    249703 91853379 7190.5
## - experience:weeks       1    267405 91871082 7190.7
## - smsa:union             1    271958 91875635 7190.7
## <none>                               91603677 7190.9
## - industry:smsa          1    409391 92013068 7191.6
## - experience:occupation  1    437316 92040993 7191.8
## - smsa:gender            1    444810 92048486 7191.8
## - occupation:union       1    507879 92111556 7192.2
## - weeks:occupation       1    527801 92131478 7192.3
## - occupation:education   1    616286 92219963 7192.9
## - gender:ethnicity       1    680823 92284500 7193.3
## - industry:south         1    893102 92496779 7194.7
## - industry:union         1   1192834 92796511 7196.6
## - weeks:gender           1   1327694 92931371 7197.5
## - union:education        1   1606155 93209831 7199.3
## - south:education        1   1746342 93350019 7200.2
## - weeks:married          1   2058363 93662040 7202.2
## 
## Step:  AIC=7189.21
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:gender      1     72569 91718895 7187.7
## - experience:married     1     75522 91721848 7187.7
## - weeks:ethnicity        1     99007 91745334 7187.8
## - south:smsa             1    100726 91747053 7187.9
## - married:union          1    109839 91756165 7187.9
## - experience:union       1    111212 91757538 7187.9
## - industry:education     1    119017 91765344 7188.0
## - union:ethnicity        1    158709 91805036 7188.2
## - weeks:south            1    165021 91811347 7188.3
## - education:ethnicity    1    197883 91844209 7188.5
## - weeks:smsa             1    245643 91891969 7188.8
## - industry:ethnicity     1    253128 91899455 7188.8
## - experience:weeks       1    259416 91905742 7188.9
## - smsa:union             1    262957 91909283 7188.9
## - experience:ethnicity   1    263720 91910046 7188.9
## - married:ethnicity      1    277158 91923484 7189.0
## <none>                               91646326 7189.2
## - industry:smsa          1    400475 92046801 7189.8
## - smsa:gender            1    434402 92080728 7190.0
## - experience:occupation  1    462841 92109168 7190.2
## - weeks:occupation       1    546883 92193209 7190.7
## - occupation:union       1    568327 92214654 7190.9
## - occupation:education   1    669547 92315874 7191.5
## - gender:ethnicity       1    907631 92553957 7193.1
## - industry:south         1    915075 92561401 7193.1
## - industry:union         1   1211283 92857609 7195.0
## - weeks:gender           1   1356513 93002839 7195.9
## - union:education        1   1565748 93212074 7197.3
## - south:education        1   1759145 93405471 7198.5
## - weeks:married          1   2074217 93720543 7200.5
## 
## Step:  AIC=7187.68
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:ethnicity + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:married     1     16454 91735349 7185.8
## - weeks:ethnicity        1     92318 91811213 7186.3
## - south:smsa             1     97940 91816835 7186.3
## - experience:union       1     99672 91818567 7186.3
## - married:union          1    109224 91828120 7186.4
## - industry:education     1    115167 91834063 7186.4
## - union:ethnicity        1    151502 91870397 7186.7
## - weeks:south            1    172388 91891283 7186.8
## - education:ethnicity    1    200577 91919472 7187.0
## - experience:weeks       1    240431 91959326 7187.2
## - industry:ethnicity     1    249329 91968224 7187.3
## - weeks:smsa             1    259857 91978752 7187.4
## - smsa:union             1    266700 91985595 7187.4
## <none>                               91718895 7187.7
## - married:ethnicity      1    364918 92083813 7188.0
## - experience:ethnicity   1    381676 92100571 7188.1
## - industry:smsa          1    400833 92119728 7188.3
## - experience:occupation  1    454555 92173450 7188.6
## - smsa:gender            1    492970 92211866 7188.9
## - weeks:occupation       1    546974 92265870 7189.2
## - occupation:union       1    598093 92316988 7189.5
## - occupation:education   1    679627 92398523 7190.1
## - industry:south         1    921381 92640276 7191.6
## - gender:ethnicity       1    959436 92678331 7191.9
## - industry:union         1   1251005 92969901 7193.7
## - weeks:gender           1   1443342 93162237 7195.0
## - union:education        1   1557988 93276884 7195.7
## - south:education        1   1725950 93444846 7196.8
## - weeks:married          1   2076553 93795448 7199.0
## 
## Step:  AIC=7185.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:ethnicity        1     95528 91830877 7184.4
## - south:smsa             1     96442 91831791 7184.4
## - experience:union       1    106702 91842051 7184.5
## - industry:education     1    114288 91849637 7184.5
## - married:union          1    116096 91851445 7184.5
## - union:ethnicity        1    150001 91885350 7184.8
## - weeks:south            1    175557 91910906 7184.9
## - education:ethnicity    1    198063 91933412 7185.1
## - experience:weeks       1    249558 91984907 7185.4
## - industry:ethnicity     1    254155 91989504 7185.4
## - weeks:smsa             1    263816 91999165 7185.5
## - smsa:union             1    266458 92001807 7185.5
## <none>                               91735349 7185.8
## - married:ethnicity      1    363824 92099173 7186.1
## - experience:ethnicity   1    365607 92100956 7186.2
## - industry:smsa          1    398609 92133958 7186.4
## - experience:occupation  1    442613 92177962 7186.6
## - smsa:gender            1    478939 92214288 7186.9
## - weeks:occupation       1    541037 92276386 7187.3
## - occupation:union       1    591791 92327140 7187.6
## - occupation:education   1    671217 92406566 7188.1
## - industry:south         1    914177 92649526 7189.7
## - gender:ethnicity       1   1006255 92741604 7190.3
## - industry:union         1   1249393 92984742 7191.8
## - weeks:gender           1   1432607 93167956 7193.0
## - union:education        1   1569011 93304360 7193.9
## - south:education        1   1765487 93500835 7195.1
## - weeks:married          1   2107284 93842633 7197.3
## 
## Step:  AIC=7184.4
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:smsa             1    103010 91933887 7183.1
## - experience:union       1    115246 91946123 7183.2
## - industry:education     1    116429 91947305 7183.2
## - weeks:south            1    142527 91973404 7183.3
## - married:union          1    147018 91977894 7183.4
## - education:ethnicity    1    156891 91987768 7183.4
## - union:ethnicity        1    161875 91992752 7183.5
## - weeks:smsa             1    213391 92044267 7183.8
## - smsa:union             1    251891 92082768 7184.0
## - experience:weeks       1    285255 92116131 7184.2
## - industry:ethnicity     1    293587 92124463 7184.3
## <none>                               91830877 7184.4
## - industry:smsa          1    402100 92232976 7185.0
## - experience:ethnicity   1    434621 92265498 7185.2
## - experience:occupation  1    444932 92275809 7185.3
## - weeks:occupation       1    480674 92311550 7185.5
## - smsa:gender            1    483644 92314520 7185.5
## - married:ethnicity      1    525658 92356535 7185.8
## - occupation:union       1    585617 92416494 7186.2
## - occupation:education   1    701610 92532486 7186.9
## - industry:south         1    901076 92731952 7188.2
## - gender:ethnicity       1   1165336 92996213 7189.9
## - industry:union         1   1272939 93103816 7190.6
## - weeks:gender           1   1400635 93231511 7191.4
## - union:education        1   1589922 93420799 7192.6
## - south:education        1   1710976 93541853 7193.4
## - weeks:married          1   2028010 93858886 7195.4
## 
## Step:  AIC=7183.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:education     1    106680 92040567 7181.8
## - experience:union       1    111457 92045344 7181.8
## - married:union          1    138956 92072843 7182.0
## - education:ethnicity    1    159058 92092945 7182.1
## - weeks:south            1    164273 92098160 7182.1
## - union:ethnicity        1    177437 92111324 7182.2
## - weeks:smsa             1    209244 92143131 7182.4
## - smsa:union             1    223837 92157724 7182.5
## - experience:weeks       1    276077 92209964 7182.9
## - industry:ethnicity     1    276553 92210440 7182.9
## <none>                               91933887 7183.1
## - industry:smsa          1    367198 92301085 7183.4
## - experience:occupation  1    445661 92379548 7183.9
## - experience:ethnicity   1    458102 92391989 7184.0
## - smsa:gender            1    485151 92419038 7184.2
## - weeks:occupation       1    496360 92430247 7184.3
## - occupation:union       1    534379 92468266 7184.5
## - married:ethnicity      1    560383 92494270 7184.7
## - occupation:education   1    701448 92635335 7185.6
## - industry:south         1    894743 92828630 7186.8
## - gender:ethnicity       1   1165663 93099550 7188.6
## - industry:union         1   1315146 93249033 7189.5
## - weeks:gender           1   1379536 93313423 7189.9
## - union:education        1   1677202 93611089 7191.8
## - weeks:married          1   2008907 93942794 7193.9
## - south:education        1   2072779 94006666 7194.3
## 
## Step:  AIC=7181.76
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:union       1    103702 92144269 7180.4
## - married:union          1    136786 92177353 7180.6
## - education:ethnicity    1    175203 92215770 7180.9
## - weeks:south            1    181940 92222507 7180.9
## - union:ethnicity        1    199964 92240531 7181.1
## - weeks:smsa             1    227771 92268338 7181.2
## - smsa:union             1    239666 92280233 7181.3
## - industry:ethnicity     1    242738 92283305 7181.3
## - experience:weeks       1    269710 92310277 7181.5
## - industry:smsa          1    308384 92348951 7181.8
## <none>                               92040567 7181.8
## - experience:ethnicity   1    467579 92508146 7182.8
## - smsa:gender            1    495308 92535875 7183.0
## - experience:occupation  1    502898 92543465 7183.0
## - married:ethnicity      1    551338 92591905 7183.3
## - weeks:occupation       1    570022 92610589 7183.4
## - occupation:union       1    571383 92611951 7183.4
## - occupation:education   1    604540 92645107 7183.7
## - industry:south         1   1036703 93077270 7186.4
## - gender:ethnicity       1   1193877 93234445 7187.4
## - weeks:gender           1   1434697 93475264 7189.0
## - union:education        1   1666677 93707244 7190.4
## - industry:union         1   1717323 93757891 7190.8
## - south:education        1   2124837 94165404 7193.3
## - weeks:married          1   2160152 94200719 7193.6
## 
## Step:  AIC=7180.43
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:union          1    165016 92309285 7179.5
## - weeks:south            1    170581 92314850 7179.5
## - education:ethnicity    1    170731 92315000 7179.5
## - union:ethnicity        1    203159 92347428 7179.7
## - experience:weeks       1    224369 92368639 7179.9
## - industry:ethnicity     1    229510 92373779 7179.9
## - weeks:smsa             1    250423 92394692 7180.0
## - industry:smsa          1    290321 92434590 7180.3
## <none>                               92144269 7180.4
## - smsa:union             1    321657 92465927 7180.5
## - experience:ethnicity   1    462747 92607016 7181.4
## - smsa:gender            1    475189 92619458 7181.5
## - married:ethnicity      1    534776 92679045 7181.9
## - weeks:occupation       1    579448 92723717 7182.2
## - occupation:union       1    674025 92818294 7182.8
## - occupation:education   1    677830 92822099 7182.8
## - experience:occupation  1    759413 92903682 7183.3
## - industry:south         1   1021806 93166075 7185.0
## - gender:ethnicity       1   1164384 93308653 7185.9
## - weeks:gender           1   1418850 93563119 7187.5
## - union:education        1   1585444 93729713 7188.6
## - industry:union         1   1729388 93873657 7189.5
## - south:education        1   2084083 94228352 7191.7
## - weeks:married          1   2163802 94308071 7192.2
## 
## Step:  AIC=7179.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - education:ethnicity    1    130462 92439747 7178.3
## - weeks:south            1    158071 92467356 7178.5
## - experience:weeks       1    217312 92526597 7178.9
## - industry:ethnicity     1    237370 92546655 7179.0
## - weeks:smsa             1    245747 92555032 7179.1
## - smsa:union             1    288921 92598206 7179.4
## - union:ethnicity        1    295944 92605229 7179.4
## <none>                               92309285 7179.5
## - industry:smsa          1    330146 92639431 7179.6
## - smsa:gender            1    446533 92755818 7180.4
## - experience:ethnicity   1    451973 92761258 7180.4
## - married:ethnicity      1    475100 92784385 7180.6
## - weeks:occupation       1    599334 92908619 7181.3
## - occupation:union       1    652610 92961895 7181.7
## - occupation:education   1    736687 93045972 7182.2
## - experience:occupation  1    794246 93103531 7182.6
## - industry:south         1   1027948 93337233 7184.1
## - gender:ethnicity       1   1140084 93449370 7184.8
## - weeks:gender           1   1343963 93653248 7186.1
## - union:education        1   1571499 93880784 7187.5
## - industry:union         1   1805383 94114668 7189.0
## - south:education        1   2057016 94366301 7190.6
## - weeks:married          1   2200786 94510071 7191.5
## 
## Step:  AIC=7178.34
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:south            1    180354 92620102 7177.5
## - experience:weeks       1    235430 92675177 7177.8
## - weeks:smsa             1    245873 92685620 7177.9
## - smsa:union             1    284711 92724459 7178.2
## - union:ethnicity        1    299872 92739619 7178.3
## - industry:smsa          1    308882 92748629 7178.3
## <none>                               92439747 7178.3
## - industry:ethnicity     1    360928 92800675 7178.7
## - married:ethnicity      1    413502 92853249 7179.0
## - smsa:gender            1    421583 92861331 7179.0
## - experience:ethnicity   1    436254 92876002 7179.1
## - weeks:occupation       1    628800 93068547 7180.4
## - occupation:union       1    641294 93081041 7180.4
## - experience:occupation  1    808729 93248476 7181.5
## - occupation:education   1    848339 93288087 7181.8
## - industry:south         1   1062655 93502402 7183.1
## - gender:ethnicity       1   1137670 93577417 7183.6
## - weeks:gender           1   1392707 93832454 7185.2
## - union:education        1   1541359 93981106 7186.2
## - industry:union         1   1869290 94309037 7188.2
## - south:education        1   2111105 94550853 7189.8
## - weeks:married          1   2333196 94772943 7191.2
## 
## Step:  AIC=7177.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:smsa + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:smsa             1    172792 92792893 7176.6
## - experience:weeks       1    228245 92848346 7177.0
## - industry:smsa          1    311667 92931768 7177.5
## <none>                               92620102 7177.5
## - union:ethnicity        1    314428 92934530 7177.5
## - smsa:union             1    320885 92940986 7177.6
## - industry:ethnicity     1    355606 92975708 7177.8
## - married:ethnicity      1    399021 93019123 7178.1
## - experience:ethnicity   1    435902 93056004 7178.3
## - smsa:gender            1    467222 93087323 7178.5
## - weeks:occupation       1    573987 93194089 7179.2
## - occupation:union       1    698568 93318670 7180.0
## - experience:occupation  1    821734 93441835 7180.8
## - occupation:education   1    845635 93465737 7180.9
## - industry:south         1   1029459 93649561 7182.1
## - gender:ethnicity       1   1176305 93796407 7183.0
## - weeks:gender           1   1377577 93997679 7184.3
## - union:education        1   1621124 94241226 7185.8
## - industry:union         1   1849255 94469357 7187.3
## - south:education        1   2169719 94789821 7189.3
## - weeks:married          1   2372053 94992154 7190.5
## 
## Step:  AIC=7176.6
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:union             1    258082 93050975 7176.3
## - experience:weeks       1    288786 93081679 7176.5
## - union:ethnicity        1    296047 93088940 7176.5
## <none>                               92792893 7176.6
## - industry:smsa          1    318661 93111554 7176.6
## - industry:ethnicity     1    359249 93152143 7176.9
## - married:ethnicity      1    398745 93191638 7177.2
## - smsa:gender            1    424866 93217760 7177.3
## - experience:ethnicity   1    442696 93235589 7177.4
## - weeks:occupation       1    487098 93279991 7177.7
## - occupation:union       1    718100 93510993 7179.2
## - occupation:education   1    871687 93664580 7180.2
## - experience:occupation  1    879035 93671929 7180.2
## - industry:south         1   1063711 93856604 7181.4
## - gender:ethnicity       1   1179928 93972821 7182.1
## - weeks:gender           1   1269071 94061964 7182.7
## - union:education        1   1530461 94323354 7184.3
## - industry:union         1   1781020 94573914 7185.9
## - south:education        1   2084738 94877631 7187.8
## - weeks:married          1   2332192 95125086 7189.4
## 
## Step:  AIC=7176.26
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - union:ethnicity        1    233127 93284103 7175.7
## <none>                               93050975 7176.3
## - experience:weeks       1    347031 93398006 7176.5
## - industry:ethnicity     1    360592 93411567 7176.6
## - smsa:gender            1    374647 93425622 7176.6
## - married:ethnicity      1    413932 93464907 7176.9
## - industry:smsa          1    434838 93485813 7177.0
## - experience:ethnicity   1    436180 93487155 7177.0
## - weeks:occupation       1    482233 93533209 7177.3
## - occupation:union       1    790925 93841900 7179.3
## - experience:occupation  1    861950 93912926 7179.7
## - occupation:education   1    888278 93939253 7179.9
## - industry:south         1   1137537 94188512 7181.5
## - gender:ethnicity       1   1203368 94254343 7181.9
## - weeks:gender           1   1292681 94343656 7182.5
## - union:education        1   1642035 94693010 7184.7
## - industry:union         1   1781824 94832799 7185.5
## - south:education        1   2149198 95200173 7187.8
## - weeks:married          1   2330415 95381390 7189.0
## 
## Step:  AIC=7175.75
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education
## 
##                         Df Sum of Sq      RSS    AIC
## <none>                               93284103 7175.7
## - experience:ethnicity   1    342374 93626477 7175.9
## - experience:weeks       1    357898 93642000 7176.0
## - married:ethnicity      1    382852 93666955 7176.2
## - smsa:gender            1    389928 93674031 7176.2
## - industry:smsa          1    431444 93715546 7176.5
## - weeks:occupation       1    454255 93738358 7176.6
## - industry:ethnicity     1    584573 93868675 7177.5
## - occupation:union       1    770225 94054327 7178.6
## - experience:occupation  1    793944 94078046 7178.8
## - occupation:education   1    794605 94078708 7178.8
## - gender:ethnicity       1   1021861 94305963 7180.2
## - industry:south         1   1150084 94434187 7181.0
## - weeks:gender           1   1244968 94529070 7181.6
## - union:education        1   1764736 95048838 7184.9
## - industry:union         1   1883835 95167938 7185.6
## - south:education        1   2103290 95387392 7187.0
## - weeks:married          1   2214309 95498411 7187.7
stepwise
## 
## Call:
## lm(formula = YM ~ experience + weeks + occupation + industry + 
##     south + smsa + married + gender + union + education + ethnicity + 
##     experience:weeks + experience:occupation + experience:ethnicity + 
##     weeks:occupation + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + married:ethnicity + 
##     gender:ethnicity + union:education, data = mydata2)
## 
## Coefficients:
##            (Intercept)              experience                   weeks  
##              -973.6307                 26.3765                 10.2584  
##            occupation1               industry1                  south1  
##             -1017.3840                251.1260                662.0379  
##                  smsa1                married1                 gender1  
##                35.8154              -1887.1285               1936.9768  
##                 union1               education              ethnicity1  
##               991.7270                 78.5235                165.6754  
##       experience:weeks  experience:occupation1   experience:ethnicity1  
##                -0.5124                  7.2153                 -9.0179  
##      weeks:occupation1          weeks:married1           weeks:gender1  
##                12.7170                 41.4631                -37.1696  
##     occupation1:union1   occupation1:education        industry1:south1  
##              -215.2853                 37.5504               -226.2304  
##        industry1:smsa1        industry1:union1    industry1:ethnicity1  
##              -122.2004               -262.7235                274.1885  
##       south1:education           smsa1:gender1     married1:ethnicity1  
##               -50.7068                207.6874                327.3527  
##     gender1:ethnicity1        union1:education  
##              -570.5685                -60.4342
# Setting the model, which is smallest AIC
experience=mydata$experience
weeks=mydata$weeks
occupation=as.numeric(mydata$occupation)
industry=as.numeric(mydata$industry)
south=as.numeric(mydata$south)
smsa=as.numeric(mydata$smsa)
married=as.numeric(mydata$married)
gender=as.numeric(mydata$gender)
union=as.numeric(mydata$union)
education=mydata$education
ethnicity=as.numeric(mydata$ethnicity)

#Create X design matrix
Xm=as.matrix(cbind(rep(1,n),experience,weeks,occupation,industry,south,smsa, married,gender,union,education,ethnicity,experience*weeks,experience*occupation,experience*ethnicity,weeks*occupation,weeks*married,weeks*gender,occupation*union,occupation*education,industry*south,industry*smsa,industry*union,industry*ethnicity,south*education,smsa*gender,married*ethnicity,gender*ethnicity, union*education))

# name of each column
colnames(Xm)=c("intercept","experience","weeks","occupation","industry","south","smsa", "married","gender","union","education","ethnicity","experience*weeks","experience*occupation","experience*ethnicity","weeks*occupation","weeks*married","weeks*gender","occupation*union","occupation*education","industry*south","industry*smsa","industry*union","industry*ethnicity","south*education","smsa*gender","married*ethnicity","gender*ethnicity", "union*education")
head(Xm)
##      intercept experience weeks occupation industry south smsa married gender
## [1,]         1          9    32          1        1     1    0       1      1
## [2,]         1         36    30          0        1     0    0       1      1
## [3,]         1         12    46          0        1     0    0       0      1
## [4,]         1         37    46          0        0     0    1       0      0
## [5,]         1         16    49          1        0     0    0       1      1
## [6,]         1         32    47          0        1     0    1       1      1
##      union education ethnicity experience*weeks experience*occupation
## [1,]     0         9         0              288                     9
## [2,]     0        11         0             1080                     0
## [3,]     1        12         0              552                     0
## [4,]     0        10         1             1702                     0
## [5,]     0        16         0              784                    16
## [6,]     0        12         0             1504                     0
##      experience*ethnicity weeks*occupation weeks*married weeks*gender
## [1,]                    0               32            32           32
## [2,]                    0                0            30           30
## [3,]                    0                0             0           46
## [4,]                   37                0             0            0
## [5,]                    0               49            49           49
## [6,]                    0                0            47           47
##      occupation*union occupation*education industry*south industry*smsa
## [1,]                0                    9              1             0
## [2,]                0                    0              0             0
## [3,]                0                    0              0             0
## [4,]                0                    0              0             0
## [5,]                0                   16              0             0
## [6,]                0                    0              0             1
##      industry*union industry*ethnicity south*education smsa*gender
## [1,]              0                  0               9           0
## [2,]              0                  0               0           0
## [3,]              1                  0               0           0
## [4,]              0                  0               0           0
## [5,]              0                  0               0           0
## [6,]              0                  0               0           1
##      married*ethnicity gender*ethnicity union*education
## [1,]                 0                0               0
## [2,]                 0                0               0
## [3,]                 0                0              12
## [4,]                 0                0               0
## [5,]                 0                0               0
## [6,]                 0                0               0


Each criterion:

\(SSE=93284103\)

\(Adj_R2=0.4156553\)

\(AIC=7175.746\)

\(BIC=7303.015\)

\(Cp=-9\)

\(PRESS=101741859\)

#Calculate each criterion
YM.martrix=cbind(c(mydata2$YM))
p = dim(Xm)[2]
beta_hat = solve(t(Xm)%*%Xm)%*%t(Xm)%*%YM.martrix
YM_hat = Xm%*%beta_hat
MSE_Full = sum((YM_hat-YM.martrix)^2)/(n-67)
SSE = sum((YM_hat-YM.martrix)^2)
SSTO = sum((YM.martrix-mean(YM.martrix))^2)
Adj_R2 = 1 - (SSE/(n-p))/(SSTO/(n-1))
AIC = n*log(SSE) - n*log(n) + 2*p
BIC = n*log(SSE) - n*log(n) + p*log(n)
Cp = SSE/MSE_Full - (n-2*p)
PRESS=function(linear.model) {
    pr <- residuals(linear.model)/(1 - lm.influence(linear.model)$hat)
    sum(pr^2)}
PRESS(lm(YM~Xm))
## [1] 101741859

Use anova table to find the P values is less than <2e-16. Therefore, we reject H0, which means not all \(\beta\) equal to 0. There are relationship between some X variables.

# Use Anova table to check the relationship
model.two=lm(YM~Xm)
ano2=aov(model.two)
summary(ano2)
##              Df   Sum Sq Mean Sq F value Pr(>F)    
## Xm           28 74252060 2651859   16.09 <2e-16 ***
## Residuals   566 93284103  164813                   
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Use t test, we can know which x variable have significant relationship on this model. If we set significant level is 0.05, we observed that the significant relationship is in industry,south,married,gender,union,education,week+married,weeks+gender,industry+south,industry+union,south+education,union+education.

# Check each x variables significant relationship
summary(model.two)
## 
## Call:
## lm(formula = YM ~ Xm)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1021.1  -222.3   -28.0   174.9  3285.6 
## 
## Coefficients: (1 not defined because of singularities)
##                           Estimate Std. Error t value Pr(>|t|)    
## (Intercept)              -973.6307   691.5078  -1.408 0.159685    
## Xmintercept                     NA         NA      NA       NA    
## Xmexperience               26.3765    16.3894   1.609 0.108095    
## Xmweeks                    10.2584    14.3605   0.714 0.475305    
## Xmoccupation            -1017.3840   455.4758  -2.234 0.025894 *  
## Xmindustry                251.1260    72.9441   3.443 0.000618 ***
## Xmsouth                   662.0379   194.7475   3.399 0.000723 ***
## Xmsmsa                     35.8154   129.5176   0.277 0.782243    
## Xmmarried               -1887.1285   538.2218  -3.506 0.000491 ***
## Xmgender                 1936.9768   637.2929   3.039 0.002480 ** 
## Xmunion                   991.7270   223.9365   4.429 1.14e-05 ***
## Xmeducation                78.5235    16.5215   4.753 2.55e-06 ***
## Xmethnicity               165.6754   211.6588   0.783 0.434103    
## Xmexperience*weeks         -0.5124     0.3477  -1.474 0.141141    
## Xmexperience*occupation     7.2153     3.2874   2.195 0.028582 *  
## Xmexperience*ethnicity     -9.0179     6.2568  -1.441 0.150052    
## Xmweeks*occupation         12.7170     7.6600   1.660 0.097433 .  
## Xmweeks*married            41.4631    11.3120   3.665 0.000270 ***
## Xmweeks*gender            -37.1696    13.5240  -2.748 0.006179 ** 
## Xmoccupation*union       -215.2853    99.5867  -2.162 0.031053 *  
## Xmoccupation*education     37.5504    17.1015   2.196 0.028516 *  
## Xmindustry*south         -226.2304    85.6410  -2.642 0.008479 ** 
## Xmindustry*smsa          -122.2004    75.5277  -1.618 0.106229    
## Xmindustry*union         -262.7235    77.7093  -3.381 0.000772 ***
## Xmindustry*ethnicity      274.1885   145.5880   1.883 0.060170 .  
## Xmsouth*education         -50.7068    14.1942  -3.572 0.000384 ***
## Xmsmsa*gender             207.6874   135.0247   1.538 0.124572    
## Xmmarried*ethnicity       327.3527   214.7810   1.524 0.128037    
## Xmgender*ethnicity       -570.5685   229.1435  -2.490 0.013060 *  
## Xmunion*education         -60.4342    18.4688  -3.272 0.001132 ** 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 406 on 566 degrees of freedom
## Multiple R-squared:  0.4432, Adjusted R-squared:  0.4157 
## F-statistic: 16.09 on 28 and 566 DF,  p-value: < 2.2e-16
##################################
##### Model diagnostics
##################################
plot(sel1) #Skewed Right

plot(sel2) #Skewed Right

########################################################################
##### Model selection: stepwise algorithms
##### Example 1: first-order models on X1 - X11, Forward selection
#########################################################################`

model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~., data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="forward")
## Start:  AIC=7468.15
## YM ~ 1
## 
##              Df Sum of Sq       RSS    AIC
## + education   1  32538301 134997861 7341.7
## + occupation  1  22992077 144544085 7382.3
## + gender      1  12829545 154706617 7422.7
## + married     1  10932833 156603329 7430.0
## + smsa        1   8127541 159408621 7440.6
## + ethnicity   1   5344585 162191577 7450.9
## + south       1   4329602 163206560 7454.6
## + experience  1   1362281 166173881 7465.3
## + union       1    995691 166540471 7466.6
## <none>                    167536162 7468.1
## + weeks       1    321828 167214334 7469.0
## + industry    1    121663 167414499 7469.7
## 
## Step:  AIC=7341.66
## YM ~ education
## 
##              Df Sum of Sq       RSS    AIC
## + gender      1  12779707 122218154 7284.5
## + married     1  10254719 124743143 7296.7
## + experience  1   6226451 128771410 7315.6
## + smsa        1   3415108 131582754 7328.4
## + industry    1   3308035 131689826 7328.9
## + ethnicity   1   2694785 132303077 7331.7
## + occupation  1   2192036 132805826 7333.9
## + south       1   2135767 132862094 7334.2
## <none>                    134997861 7341.7
## + union       1    330373 134667489 7342.2
## + weeks       1    320629 134677232 7342.2
## 
## Step:  AIC=7284.49
## YM ~ education + gender
## 
##              Df Sum of Sq       RSS    AIC
## + smsa        1   5133833 117084321 7261.0
## + experience  1   4667646 117550508 7263.3
## + occupation  1   3076803 119141352 7271.3
## + south       1   1530433 120687721 7279.0
## + industry    1   1421780 120796374 7279.5
## + married     1    885628 121332526 7282.2
## + ethnicity   1    830636 121387519 7282.4
## <none>                    122218154 7284.5
## + weeks       1     64671 122153483 7286.2
## + union       1     10215 122207940 7286.4
## 
## Step:  AIC=7260.96
## YM ~ education + gender + smsa
## 
##              Df Sum of Sq       RSS    AIC
## + experience  1   3681824 113402497 7243.9
## + occupation  1   2438824 114645498 7250.4
## + ethnicity   1   1494428 115589893 7255.3
## + industry    1   1289920 115794402 7256.4
## + married     1   1059185 116025137 7257.5
## + south       1    881624 116202697 7258.5
## <none>                    117084321 7261.0
## + weeks       1     32761 117051560 7262.8
## + union       1      5150 117079172 7262.9
## 
## Step:  AIC=7243.95
## YM ~ education + gender + smsa + experience
## 
##              Df Sum of Sq       RSS    AIC
## + occupation  1   2112437 111290061 7234.8
## + ethnicity   1   1599078 111803420 7237.5
## + industry    1    897795 112504702 7241.2
## + south       1    666655 112735843 7242.4
## + married     1    580521 112821976 7242.9
## <none>                    113402497 7243.9
## + weeks       1    175973 113226525 7245.0
## + union       1      2300 113400198 7245.9
## 
## Step:  AIC=7234.76
## YM ~ education + gender + smsa + experience + occupation
## 
##             Df Sum of Sq       RSS    AIC
## + ethnicity  1   1490793 109799268 7228.7
## + industry   1   1277208 110012853 7229.9
## + south      1    898041 110392020 7231.9
## + married    1    592449 110697611 7233.6
## <none>                   111290061 7234.8
## + weeks      1    150302 111139759 7236.0
## + union      1    149432 111140629 7236.0
## 
## Step:  AIC=7228.73
## YM ~ education + gender + smsa + experience + occupation + ethnicity
## 
##            Df Sum of Sq       RSS    AIC
## + industry  1   1141696 108657572 7224.5
## + south     1    646695 109152573 7227.2
## + married   1    413169 109386099 7228.5
## <none>                  109799268 7228.7
## + union     1    157390 109641878 7229.9
## + weeks     1    111460 109687807 7230.1
## 
## Step:  AIC=7224.51
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry
## 
##           Df Sum of Sq       RSS    AIC
## + south    1    488609 108168963 7223.8
## + married  1    367353 108290219 7224.5
## <none>                 108657572 7224.5
## + weeks    1    126218 108531354 7225.8
## + union    1    114357 108543214 7225.9
## 
## Step:  AIC=7223.83
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south
## 
##           Df Sum of Sq       RSS    AIC
## <none>                 108168963 7223.8
## + married  1    361271 107807692 7223.8
## + weeks    1    111973 108056989 7225.2
## + union    1     51154 108117809 7225.6
## 
## Call:
## lm(formula = YM ~ education + gender + smsa + experience + occupation + 
##     ethnicity + industry + south, data = mydata2)
## 
## Coefficients:
## (Intercept)    education      gender1        smsa1   experience  occupation1  
##    -417.552       65.085      426.176      171.077        6.711      172.884  
##  ethnicity1    industry1       south1  
##    -178.293       88.607      -65.313
step(modelF, scope=list(lower=model0, upper=modelF), direction="forward")
## Start:  AIC=7226.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity
## 
## Call:
## lm(formula = YM ~ experience + weeks + occupation + industry + 
##     south + smsa + married + gender + union + education + ethnicity, 
##     data = mydata2)
## 
## Coefficients:
## (Intercept)   experience        weeks  occupation1    industry1       south1  
##    -564.888        6.578        2.962      180.637       86.693      -59.662  
##       smsa1     married1      gender1       union1    education   ethnicity1  
##     169.833       85.620      344.516       25.782       65.257     -167.249
#########################################################################
##### Model selection: stepwise algorithms
##### Example 2: first-order models on X1 - X8, Backward elimination
#########################################################################

model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~., data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="backward")
## Start:  AIC=7468.15
## YM ~ 1
## 
## Call:
## lm(formula = YM ~ 1, data = mydata2)
## 
## Coefficients:
## (Intercept)  
##        1148
step(modelF, scope=list(lower=model0, upper=modelF), direction="backward")
## Start:  AIC=7226.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - union       1     70374 107710551 7225.3
## - weeks       1    130014 107770192 7225.6
## - married     1    325339 107965516 7226.7
## <none>                    107640177 7226.9
## - south       1    394974 108035151 7227.1
## - industry    1    938953 108579131 7230.1
## - ethnicity   1   1001378 108641556 7230.4
## - occupation  1   2540232 110180410 7238.8
## - experience  1   2626322 110266499 7239.3
## - gender      1   3413478 111053656 7243.5
## - smsa        1   3505148 111145325 7244.0
## - education   1  10393407 118033584 7279.8
## 
## Step:  AIC=7225.31
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - weeks       1     97140 107807692 7223.8
## - married     1    346438 108056989 7225.2
## <none>                    107710551 7225.3
## - south       1    469427 108179978 7225.9
## - industry    1    956829 108667380 7228.6
## - ethnicity   1    986781 108697333 7228.7
## - occupation  1   2500900 110211451 7237.0
## - experience  1   2591635 110302186 7237.5
## - gender      1   3480415 111190966 7242.2
## - smsa        1   3625406 111335957 7243.0
## - education   1  10323251 118033802 7277.8
## 
## Step:  AIC=7223.84
## YM ~ experience + occupation + industry + south + smsa + married + 
##     gender + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - married     1    361271 108168963 7223.8
## <none>                    107807692 7223.8
## - south       1    482528 108290219 7224.5
## - industry    1    942673 108750365 7227.0
## - ethnicity   1   1011466 108819157 7227.4
## - experience  1   2506604 110314296 7235.5
## - occupation  1   2522219 110329911 7235.6
## - gender      1   3538711 111346403 7241.1
## - smsa        1   3689667 111497358 7241.9
## - education   1  10246852 118054543 7275.9
## 
## Step:  AIC=7223.83
## YM ~ experience + occupation + industry + south + smsa + gender + 
##     education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## <none>                    108168963 7223.8
## - south       1    488609 108657572 7224.5
## - industry    1    983610 109152573 7227.2
## - ethnicity   1   1152933 109321896 7228.1
## - occupation  1   2515049 110684012 7235.5
## - experience  1   2840056 111009018 7237.3
## - smsa        1   3600308 111769271 7241.3
## - gender      1   9829554 117998516 7273.6
## - education   1  10453146 118622108 7276.7
## 
## Call:
## lm(formula = YM ~ experience + occupation + industry + south + 
##     smsa + gender + education + ethnicity, data = mydata2)
## 
## Coefficients:
## (Intercept)   experience  occupation1    industry1       south1        smsa1  
##    -417.552        6.711      172.884       88.607      -65.313      171.077  
##     gender1    education   ethnicity1  
##     426.176       65.085     -178.293
#########################################################################
##### Model selection: stepwise algorithms
##### Example 3: first-order models on X1 - X8, Forward stepwise
#########################################################################
model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~., data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="both")
## Start:  AIC=7468.15
## YM ~ 1
## 
##              Df Sum of Sq       RSS    AIC
## + education   1  32538301 134997861 7341.7
## + occupation  1  22992077 144544085 7382.3
## + gender      1  12829545 154706617 7422.7
## + married     1  10932833 156603329 7430.0
## + smsa        1   8127541 159408621 7440.6
## + ethnicity   1   5344585 162191577 7450.9
## + south       1   4329602 163206560 7454.6
## + experience  1   1362281 166173881 7465.3
## + union       1    995691 166540471 7466.6
## <none>                    167536162 7468.1
## + weeks       1    321828 167214334 7469.0
## + industry    1    121663 167414499 7469.7
## 
## Step:  AIC=7341.66
## YM ~ education
## 
##              Df Sum of Sq       RSS    AIC
## + gender      1  12779707 122218154 7284.5
## + married     1  10254719 124743143 7296.7
## + experience  1   6226451 128771410 7315.6
## + smsa        1   3415108 131582754 7328.4
## + industry    1   3308035 131689826 7328.9
## + ethnicity   1   2694785 132303077 7331.7
## + occupation  1   2192036 132805826 7333.9
## + south       1   2135767 132862094 7334.2
## <none>                    134997861 7341.7
## + union       1    330373 134667489 7342.2
## + weeks       1    320629 134677232 7342.2
## - education   1  32538301 167536162 7468.1
## 
## Step:  AIC=7284.49
## YM ~ education + gender
## 
##              Df Sum of Sq       RSS    AIC
## + smsa        1   5133833 117084321 7261.0
## + experience  1   4667646 117550508 7263.3
## + occupation  1   3076803 119141352 7271.3
## + south       1   1530433 120687721 7279.0
## + industry    1   1421780 120796374 7279.5
## + married     1    885628 121332526 7282.2
## + ethnicity   1    830636 121387519 7282.4
## <none>                    122218154 7284.5
## + weeks       1     64671 122153483 7286.2
## + union       1     10215 122207940 7286.4
## - gender      1  12779707 134997861 7341.7
## - education   1  32488463 154706617 7422.7
## 
## Step:  AIC=7260.96
## YM ~ education + gender + smsa
## 
##              Df Sum of Sq       RSS    AIC
## + experience  1   3681824 113402497 7243.9
## + occupation  1   2438824 114645498 7250.4
## + ethnicity   1   1494428 115589893 7255.3
## + industry    1   1289920 115794402 7256.4
## + married     1   1059185 116025137 7257.5
## + south       1    881624 116202697 7258.5
## <none>                    117084321 7261.0
## + weeks       1     32761 117051560 7262.8
## + union       1      5150 117079172 7262.9
## - smsa        1   5133833 122218154 7284.5
## - gender      1  14498432 131582754 7328.4
## - education   1  26944998 144029319 7382.2
## 
## Step:  AIC=7243.95
## YM ~ education + gender + smsa + experience
## 
##              Df Sum of Sq       RSS    AIC
## + occupation  1   2112437 111290061 7234.8
## + ethnicity   1   1599078 111803420 7237.5
## + industry    1    897795 112504702 7241.2
## + south       1    666655 112735843 7242.4
## + married     1    580521 112821976 7242.9
## <none>                    113402497 7243.9
## + weeks       1    175973 113226525 7245.0
## + union       1      2300 113400198 7245.9
## - experience  1   3681824 117084321 7261.0
## - smsa        1   4148011 117550508 7263.3
## - gender      1  12786981 126189478 7305.5
## - education   1  30244311 143646808 7382.6
## 
## Step:  AIC=7234.76
## YM ~ education + gender + smsa + experience + occupation
## 
##              Df Sum of Sq       RSS    AIC
## + ethnicity   1   1490793 109799268 7228.7
## + industry    1   1277208 110012853 7229.9
## + south       1    898041 110392020 7231.9
## + married     1    592449 110697611 7233.6
## <none>                    111290061 7234.8
## + weeks       1    150302 111139759 7236.0
## + union       1    149432 111140629 7236.0
## - occupation  1   2112437 113402497 7243.9
## - experience  1   3355437 114645498 7250.4
## - smsa        1   3658161 114948222 7252.0
## - education   1  11406668 122696729 7290.8
## - gender      1  13469904 124759965 7300.7
## 
## Step:  AIC=7228.73
## YM ~ education + gender + smsa + experience + occupation + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## + industry    1   1141696 108657572 7224.5
## + south       1    646695 109152573 7227.2
## + married     1    413169 109386099 7228.5
## <none>                    109799268 7228.7
## + union       1    157390 109641878 7229.9
## + weeks       1    111460 109687807 7230.1
## - ethnicity   1   1490793 111290061 7234.8
## - occupation  1   2004152 111803420 7237.5
## - experience  1   3459487 113258754 7245.2
## - smsa        1   4229138 114028405 7249.2
## - education   1  10612905 120412173 7281.6
## - gender      1  11246775 121046043 7284.8
## 
## Step:  AIC=7224.51
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry
## 
##              Df Sum of Sq       RSS    AIC
## + south       1    488609 108168963 7223.8
## + married     1    367353 108290219 7224.5
## <none>                    108657572 7224.5
## + weeks       1    126218 108531354 7225.8
## + union       1    114357 108543214 7225.9
## - industry    1   1141696 109799268 7228.7
## - ethnicity   1   1355281 110012853 7229.9
## - occupation  1   2356722 111014294 7235.3
## - experience  1   2999852 111657424 7238.7
## - smsa        1   4093493 112751065 7244.5
## - gender      1   9943170 118600741 7274.6
## - education   1  11252407 119909979 7281.1
## 
## Step:  AIC=7223.83
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south
## 
##              Df Sum of Sq       RSS    AIC
## <none>                    108168963 7223.8
## + married     1    361271 107807692 7223.8
## - south       1    488609 108657572 7224.5
## + weeks       1    111973 108056989 7225.2
## + union       1     51154 108117809 7225.6
## - industry    1    983610 109152573 7227.2
## - ethnicity   1   1152933 109321896 7228.1
## - occupation  1   2515049 110684012 7235.5
## - experience  1   2840056 111009018 7237.3
## - smsa        1   3600308 111769271 7241.3
## - gender      1   9829554 117998516 7273.6
## - education   1  10453146 118622108 7276.7
## 
## Call:
## lm(formula = YM ~ education + gender + smsa + experience + occupation + 
##     ethnicity + industry + south, data = mydata2)
## 
## Coefficients:
## (Intercept)    education      gender1        smsa1   experience  occupation1  
##    -417.552       65.085      426.176      171.077        6.711      172.884  
##  ethnicity1    industry1       south1  
##    -178.293       88.607      -65.313
step(modelF, scope=list(lower=model0, upper=modelF), direction="both")
## Start:  AIC=7226.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - union       1     70374 107710551 7225.3
## - weeks       1    130014 107770192 7225.6
## - married     1    325339 107965516 7226.7
## <none>                    107640177 7226.9
## - south       1    394974 108035151 7227.1
## - industry    1    938953 108579131 7230.1
## - ethnicity   1   1001378 108641556 7230.4
## - occupation  1   2540232 110180410 7238.8
## - experience  1   2626322 110266499 7239.3
## - gender      1   3413478 111053656 7243.5
## - smsa        1   3505148 111145325 7244.0
## - education   1  10393407 118033584 7279.8
## 
## Step:  AIC=7225.31
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - weeks       1     97140 107807692 7223.8
## - married     1    346438 108056989 7225.2
## <none>                    107710551 7225.3
## - south       1    469427 108179978 7225.9
## + union       1     70374 107640177 7226.9
## - industry    1    956829 108667380 7228.6
## - ethnicity   1    986781 108697333 7228.7
## - occupation  1   2500900 110211451 7237.0
## - experience  1   2591635 110302186 7237.5
## - gender      1   3480415 111190966 7242.2
## - smsa        1   3625406 111335957 7243.0
## - education   1  10323251 118033802 7277.8
## 
## Step:  AIC=7223.84
## YM ~ experience + occupation + industry + south + smsa + married + 
##     gender + education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## - married     1    361271 108168963 7223.8
## <none>                    107807692 7223.8
## - south       1    482528 108290219 7224.5
## + weeks       1     97140 107710551 7225.3
## + union       1     37500 107770192 7225.6
## - industry    1    942673 108750365 7227.0
## - ethnicity   1   1011466 108819157 7227.4
## - experience  1   2506604 110314296 7235.5
## - occupation  1   2522219 110329911 7235.6
## - gender      1   3538711 111346403 7241.1
## - smsa        1   3689667 111497358 7241.9
## - education   1  10246852 118054543 7275.9
## 
## Step:  AIC=7223.83
## YM ~ experience + occupation + industry + south + smsa + gender + 
##     education + ethnicity
## 
##              Df Sum of Sq       RSS    AIC
## <none>                    108168963 7223.8
## + married     1    361271 107807692 7223.8
## - south       1    488609 108657572 7224.5
## + weeks       1    111973 108056989 7225.2
## + union       1     51154 108117809 7225.6
## - industry    1    983610 109152573 7227.2
## - ethnicity   1   1152933 109321896 7228.1
## - occupation  1   2515049 110684012 7235.5
## - experience  1   2840056 111009018 7237.3
## - smsa        1   3600308 111769271 7241.3
## - gender      1   9829554 117998516 7273.6
## - education   1  10453146 118622108 7276.7
## 
## Call:
## lm(formula = YM ~ experience + occupation + industry + south + 
##     smsa + gender + education + ethnicity, data = mydata2)
## 
## Coefficients:
## (Intercept)   experience  occupation1    industry1       south1        smsa1  
##    -417.552        6.711      172.884       88.607      -65.313      171.077  
##     gender1    education   ethnicity1  
##     426.176       65.085     -178.293
#########################################################################
##### Model selection: stepwise algorithms
##### Example 4: first-order models and models with interactions, Forward selection
#########################################################################

model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~.^2, data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="forward")
## Start:  AIC=7468.15
## YM ~ 1
## 
##              Df Sum of Sq       RSS    AIC
## + education   1  32538301 134997861 7341.7
## + occupation  1  22992077 144544085 7382.3
## + gender      1  12829545 154706617 7422.7
## + married     1  10932833 156603329 7430.0
## + smsa        1   8127541 159408621 7440.6
## + ethnicity   1   5344585 162191577 7450.9
## + south       1   4329602 163206560 7454.6
## + experience  1   1362281 166173881 7465.3
## + union       1    995691 166540471 7466.6
## <none>                    167536162 7468.1
## + weeks       1    321828 167214334 7469.0
## + industry    1    121663 167414499 7469.7
## 
## Step:  AIC=7341.66
## YM ~ education
## 
##              Df Sum of Sq       RSS    AIC
## + gender      1  12779707 122218154 7284.5
## + married     1  10254719 124743143 7296.7
## + experience  1   6226451 128771410 7315.6
## + smsa        1   3415108 131582754 7328.4
## + industry    1   3308035 131689826 7328.9
## + ethnicity   1   2694785 132303077 7331.7
## + occupation  1   2192036 132805826 7333.9
## + south       1   2135767 132862094 7334.2
## <none>                    134997861 7341.7
## + union       1    330373 134667489 7342.2
## + weeks       1    320629 134677232 7342.2
## 
## Step:  AIC=7284.49
## YM ~ education + gender
## 
##                    Df Sum of Sq       RSS    AIC
## + smsa              1   5133833 117084321 7261.0
## + experience        1   4667646 117550508 7263.3
## + occupation        1   3076803 119141352 7271.3
## + south             1   1530433 120687721 7279.0
## + industry          1   1421780 120796374 7279.5
## + married           1    885628 121332526 7282.2
## + ethnicity         1    830636 121387519 7282.4
## <none>                          122218154 7284.5
## + weeks             1     64671 122153483 7286.2
## + gender:education  1     41500 122176655 7286.3
## + union             1     10215 122207940 7286.4
## 
## Step:  AIC=7260.96
## YM ~ education + gender + smsa
## 
##                    Df Sum of Sq       RSS    AIC
## + experience        1   3681824 113402497 7243.9
## + occupation        1   2438824 114645498 7250.4
## + ethnicity         1   1494428 115589893 7255.3
## + industry          1   1289920 115794402 7256.4
## + married           1   1059185 116025137 7257.5
## + south             1    881624 116202697 7258.5
## + smsa:education    1    494481 116589841 7260.4
## <none>                          117084321 7261.0
## + smsa:gender       1     90405 116993916 7262.5
## + weeks             1     32761 117051560 7262.8
## + gender:education  1     28736 117055586 7262.8
## + union             1      5150 117079172 7262.9
## 
## Step:  AIC=7243.95
## YM ~ education + gender + smsa + experience
## 
##                        Df Sum of Sq       RSS    AIC
## + occupation            1   2112437 111290061 7234.8
## + ethnicity             1   1599078 111803420 7237.5
## + industry              1    897795 112504702 7241.2
## + south                 1    666655 112735843 7242.4
## + smsa:education        1    598877 112803621 7242.8
## + married               1    580521 112821976 7242.9
## <none>                              113402497 7243.9
## + experience:gender     1    335405 113067093 7244.2
## + smsa:gender           1    177714 113224783 7245.0
## + weeks                 1    175973 113226525 7245.0
## + gender:education      1     53580 113348918 7245.7
## + experience:education  1     18554 113383944 7245.8
## + union                 1      2300 113400198 7245.9
## + experience:smsa       1       948 113401550 7245.9
## 
## Step:  AIC=7234.76
## YM ~ education + gender + smsa + experience + occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + ethnicity              1   1490793 109799268 7228.7
## + occupation:education   1   1385398 109904663 7229.3
## + industry               1   1277208 110012853 7229.9
## + south                  1    898041 110392020 7231.9
## + married                1    592449 110697611 7233.6
## + smsa:education         1    424265 110865796 7234.5
## <none>                               111290061 7234.8
## + experience:occupation  1    346486 110943575 7234.9
## + experience:gender      1    197085 111092976 7235.7
## + smsa:gender            1    175541 111114520 7235.8
## + weeks                  1    150302 111139759 7236.0
## + union                  1    149432 111140629 7236.0
## + occupation:gender      1     78695 111211366 7236.3
## + experience:education   1     77734 111212327 7236.3
## + gender:education       1     60964 111229097 7236.4
## + occupation:smsa        1     29381 111260680 7236.6
## + experience:smsa        1      9924 111280137 7236.7
## 
## Step:  AIC=7228.73
## YM ~ education + gender + smsa + experience + occupation + ethnicity
## 
##                         Df Sum of Sq       RSS    AIC
## + occupation:education   1   1353525 108445743 7223.4
## + industry               1   1141696 108657572 7224.5
## + occupation:ethnicity   1   1066339 108732929 7224.9
## + south                  1    646695 109152573 7227.2
## + education:ethnicity    1    493449 109305819 7228.1
## + married                1    413169 109386099 7228.5
## + experience:occupation  1    383390 109415878 7228.7
## <none>                               109799268 7228.7
## + occupation:gender      1    362778 109436490 7228.8
## + smsa:education         1    362161 109437106 7228.8
## + gender:ethnicity       1    253895 109545373 7229.4
## + gender:education       1    218448 109580820 7229.5
## + union                  1    157390 109641878 7229.9
## + experience:education   1    137568 109661700 7230.0
## + weeks                  1    111460 109687807 7230.1
## + experience:ethnicity   1     75548 109723720 7230.3
## + smsa:ethnicity         1     74879 109724389 7230.3
## + smsa:gender            1     70979 109728288 7230.3
## + experience:gender      1     51982 109747285 7230.5
## + experience:smsa        1     20688 109778580 7230.6
## + occupation:smsa        1     13851 109785417 7230.7
## 
## Step:  AIC=7223.35
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     education:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + industry               1   1067950 107377793 7219.5
## + occupation:ethnicity   1    832174 107613568 7220.8
## + experience:occupation  1    789177 107656565 7221.0
## + south                  1    721189 107724554 7221.4
## + married                1    496447 107949296 7222.6
## + experience:education   1    383380 108062363 7223.2
## <none>                               108445743 7223.4
## + education:ethnicity    1    311668 108134075 7223.6
## + occupation:gender      1    306264 108139479 7223.7
## + gender:ethnicity       1    281068 108164675 7223.8
## + gender:education       1    263202 108182541 7223.9
## + union                  1    213582 108232161 7224.2
## + weeks                  1    199242 108246501 7224.3
## + smsa:education         1    114026 108331716 7224.7
## + experience:ethnicity   1     88428 108357314 7224.9
## + smsa:gender            1     42042 108403701 7225.1
## + smsa:ethnicity         1     37358 108408385 7225.1
## + experience:smsa        1     36806 108408937 7225.2
## + experience:gender      1     36382 108409361 7225.2
## + occupation:smsa        1       331 108445412 7225.4
## 
## Step:  AIC=7219.47
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + industry:education     1   1124480 106253313 7215.2
## + occupation:industry    1    909910 106467882 7216.4
## + occupation:ethnicity   1    810821 106566971 7217.0
## + experience:occupation  1    684802 106692991 7217.7
## + south                  1    557481 106820312 7218.4
## + married                1    445524 106932269 7219.0
## <none>                               107377793 7219.5
## + gender:education       1    307168 107070625 7219.8
## + education:ethnicity    1    303694 107074099 7219.8
## + experience:education   1    302250 107075543 7219.8
## + industry:smsa          1    280595 107097198 7219.9
## + gender:ethnicity       1    263658 107114135 7220.0
## + occupation:gender      1    258262 107119531 7220.0
## + weeks                  1    215449 107162344 7220.3
## + union                  1    163053 107214740 7220.6
## + industry:ethnicity     1     90010 107287783 7221.0
## + experience:ethnicity   1     80121 107297671 7221.0
## + smsa:education         1     73622 107304170 7221.1
## + smsa:ethnicity         1     48461 107329331 7221.2
## + smsa:gender            1     48333 107329460 7221.2
## + experience:gender      1     46302 107331491 7221.2
## + industry:gender        1     39298 107338495 7221.2
## + experience:industry    1     22060 107355733 7221.3
## + experience:smsa        1     11669 107366124 7221.4
## + occupation:smsa        1       864 107376929 7221.5
## 
## Step:  AIC=7215.2
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry
## 
##                         Df Sum of Sq       RSS    AIC
## + occupation:ethnicity   1    676151 105577162 7213.4
## + industry:smsa          1    560151 105693162 7214.1
## + experience:occupation  1    535565 105717748 7214.2
## + married                1    510970 105742344 7214.3
## + south                  1    485529 105767784 7214.5
## <none>                               106253313 7215.2
## + union                  1    335354 105917959 7215.3
## + education:ethnicity    1    200010 106053304 7216.1
## + industry:ethnicity     1    198607 106054706 7216.1
## + gender:ethnicity       1    189630 106063683 7216.1
## + experience:education   1    184881 106068433 7216.2
## + occupation:gender      1    154977 106098336 7216.3
## + occupation:industry    1    146477 106106836 7216.4
## + weeks                  1    142935 106110378 7216.4
## + gender:education       1    120361 106132952 7216.5
## + industry:gender        1     57349 106195964 7216.9
## + smsa:education         1     53934 106199379 7216.9
## + experience:ethnicity   1     52127 106201186 7216.9
## + experience:gender      1     44874 106208439 7216.9
## + smsa:gender            1     33897 106219417 7217.0
## + smsa:ethnicity         1     14163 106239150 7217.1
## + experience:smsa        1     13161 106240153 7217.1
## + occupation:smsa        1      1613 106251700 7217.2
## + experience:industry    1      1005 106252308 7217.2
## 
## Step:  AIC=7213.4
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity
## 
##                         Df Sum of Sq       RSS    AIC
## + industry:smsa          1    644500 104932662 7211.8
## + experience:occupation  1    552534 105024628 7212.3
## + south                  1    464656 105112506 7212.8
## + married                1    440262 105136900 7212.9
## + union                  1    371162 105206000 7213.3
## <none>                               105577162 7213.4
## + experience:education   1    221586 105355576 7214.2
## + weeks                  1    138933 105438229 7214.6
## + occupation:industry    1    118387 105458775 7214.7
## + gender:education       1     94754 105482408 7214.9
## + experience:gender      1     86202 105490960 7214.9
## + smsa:education         1     79477 105497685 7215.0
## + experience:ethnicity   1     76083 105501079 7215.0
## + industry:ethnicity     1     74014 105503148 7215.0
## + smsa:gender            1     71543 105505619 7215.0
## + occupation:gender      1     61415 105515747 7215.1
## + gender:ethnicity       1     45833 105531329 7215.1
## + industry:gender        1     36856 105540306 7215.2
## + experience:smsa        1     16310 105560853 7215.3
## + occupation:smsa        1      6967 105570195 7215.4
## + education:ethnicity    1       989 105576173 7215.4
## + smsa:ethnicity         1       483 105576679 7215.4
## + experience:industry    1       385 105576777 7215.4
## 
## Step:  AIC=7211.76
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity + 
##     smsa:industry
## 
##                         Df Sum of Sq       RSS    AIC
## + experience:occupation  1    530344 104402318 7210.7
## + south                  1    484279 104448383 7211.0
## + married                1    450919 104481743 7211.2
## <none>                               104932662 7211.8
## + union                  1    327870 104604792 7211.9
## + experience:education   1    181278 104751384 7212.7
## + smsa:gender            1    172324 104760338 7212.8
## + industry:ethnicity     1    156178 104776484 7212.9
## + occupation:industry    1    153909 104778754 7212.9
## + weeks                  1    119779 104812883 7213.1
## + experience:gender      1    112328 104820334 7213.1
## + experience:ethnicity   1     91884 104840779 7213.2
## + gender:education       1     86676 104845986 7213.3
## + occupation:gender      1     72525 104860137 7213.3
## + industry:gender        1     66698 104865964 7213.4
## + experience:smsa        1     49222 104883440 7213.5
## + gender:ethnicity       1     25558 104907104 7213.6
## + occupation:smsa        1     12806 104919857 7213.7
## + experience:industry    1      8722 104923940 7213.7
## + education:ethnicity    1      5070 104927592 7213.7
## + smsa:education         1      3164 104929499 7213.7
## + smsa:ethnicity         1        47 104932615 7213.8
## 
## Step:  AIC=7210.74
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity + 
##     smsa:industry + experience:occupation
## 
##                        Df Sum of Sq       RSS    AIC
## + south                 1    471832 103930487 7210.0
## + married               1    453018 103949300 7210.2
## <none>                              104402318 7210.7
## + union                 1    303878 104098440 7211.0
## + industry:ethnicity    1    197575 104204743 7211.6
## + smsa:gender           1    161451 104240867 7211.8
## + weeks                 1    108363 104293955 7212.1
## + occupation:industry   1    105173 104297145 7212.1
## + experience:gender     1    101740 104300578 7212.2
## + industry:gender       1     73553 104328765 7212.3
## + gender:education      1     64519 104337800 7212.4
## + experience:ethnicity  1     61764 104340554 7212.4
## + experience:industry   1     52310 104350008 7212.4
## + occupation:gender     1     43082 104359236 7212.5
## + gender:ethnicity      1     32020 104370298 7212.6
## + occupation:smsa       1     28581 104373737 7212.6
## + experience:smsa       1     14214 104388105 7212.7
## + education:ethnicity   1      6402 104395916 7212.7
## + experience:education  1       898 104401421 7212.7
## + smsa:ethnicity        1       100 104402218 7212.7
## + smsa:education        1        24 104402294 7212.7
## 
## Step:  AIC=7210.05
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation
## 
##                        Df Sum of Sq       RSS    AIC
## + south:education       1    519525 103410961 7209.1
## + married               1    447670 103482816 7209.5
## <none>                              103930487 7210.0
## + industry:south        1    229392 103701095 7210.7
## + industry:ethnicity    1    198305 103732181 7210.9
## + union                 1    192120 103738367 7210.9
## + south:smsa            1    161737 103768749 7211.1
## + smsa:gender           1    154361 103776126 7211.2
## + experience:south      1    124131 103806355 7211.3
## + experience:gender     1    107397 103823089 7211.4
## + occupation:industry   1     99264 103831222 7211.5
## + weeks                 1     98545 103831941 7211.5
## + industry:gender       1     73494 103856993 7211.6
## + experience:ethnicity  1     57734 103872753 7211.7
## + gender:education      1     49484 103881003 7211.8
## + gender:ethnicity      1     40744 103889743 7211.8
## + occupation:gender     1     33842 103896645 7211.9
## + south:gender          1     33772 103896715 7211.9
## + south:ethnicity       1     30036 103900451 7211.9
## + experience:industry   1     27283 103903204 7211.9
## + occupation:south      1     24829 103905658 7211.9
## + smsa:education        1     13291 103917196 7212.0
## + occupation:smsa       1     11076 103919410 7212.0
## + education:ethnicity   1      8894 103921593 7212.0
## + experience:smsa       1      6650 103923837 7212.0
## + smsa:ethnicity        1      3178 103927308 7212.0
## + experience:education  1       582 103929905 7212.0
## 
## Step:  AIC=7209.07
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south
## 
##                        Df Sum of Sq       RSS    AIC
## + industry:south        1    551781 102859180 7207.9
## + married               1    417873 102993088 7208.7
## <none>                              103410961 7209.1
## + union                 1    223565 103187397 7209.8
## + industry:ethnicity    1    186588 103224374 7210.0
## + smsa:gender           1    164018 103246944 7210.1
## + experience:gender     1    157590 103253371 7210.2
## + weeks                 1    138772 103272190 7210.3
## + occupation:south      1    124031 103286930 7210.4
## + south:ethnicity       1     64933 103346029 7210.7
## + occupation:industry   1     63574 103347387 7210.7
## + industry:gender       1     46721 103364240 7210.8
## + experience:ethnicity  1     45195 103365766 7210.8
## + south:smsa            1     45100 103365862 7210.8
## + experience:industry   1     42364 103368598 7210.8
## + south:gender          1     40530 103370431 7210.8
## + gender:ethnicity      1     40192 103370769 7210.8
## + gender:education      1     40048 103370913 7210.8
## + experience:south      1     34167 103376794 7210.9
## + occupation:gender     1     33210 103377751 7210.9
## + occupation:smsa       1     25832 103385130 7210.9
## + experience:smsa       1     17478 103393483 7211.0
## + experience:education  1      5433 103405528 7211.0
## + smsa:education        1      4209 103406752 7211.0
## + education:ethnicity   1      3080 103407881 7211.1
## + smsa:ethnicity        1        41 103410920 7211.1
## 
## Step:  AIC=7207.88
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south + industry:south
## 
##                        Df Sum of Sq       RSS    AIC
## + married               1    421610 102437569 7207.4
## <none>                              102859180 7207.9
## + industry:ethnicity    1    288163 102571017 7208.2
## + union                 1    204920 102654260 7208.7
## + smsa:gender           1    170512 102688668 7208.9
## + experience:gender     1    149982 102709198 7209.0
## + weeks                 1    126871 102732309 7209.2
## + south:ethnicity       1     96035 102763145 7209.3
## + occupation:industry   1     72664 102786516 7209.5
## + industry:gender       1     56754 102802426 7209.6
## + south:smsa            1     56696 102802484 7209.6
## + occupation:south      1     56655 102802525 7209.6
## + gender:education      1     55718 102803462 7209.6
## + experience:ethnicity  1     47454 102811726 7209.6
## + occupation:gender     1     43619 102815561 7209.6
## + occupation:smsa       1     33120 102826060 7209.7
## + experience:south      1     28202 102830978 7209.7
## + gender:ethnicity      1     26742 102832438 7209.7
## + experience:industry   1     23980 102835200 7209.7
## + experience:smsa       1     13352 102845828 7209.8
## + experience:education  1      7933 102851246 7209.8
## + education:ethnicity   1      5026 102854154 7209.9
## + south:gender          1      5016 102854163 7209.9
## + smsa:education        1      2611 102856568 7209.9
## + smsa:ethnicity        1      1097 102858083 7209.9
## 
## Step:  AIC=7207.44
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + married + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south + industry:south
## 
##                        Df Sum of Sq       RSS    AIC
## <none>                              102437569 7207.4
## + industry:ethnicity    1    260702 102176867 7207.9
## + smsa:gender           1    179014 102258555 7208.4
## + union                 1    176884 102260686 7208.4
## + experience:gender     1    141401 102296169 7208.6
## + weeks                 1    109027 102328542 7208.8
## + smsa:married          1     96432 102341138 7208.9
## + occupation:industry   1     86460 102351110 7208.9
## + experience:ethnicity  1     78662 102358907 7209.0
## + industry:married      1     76039 102361530 7209.0
## + south:ethnicity       1     68629 102368941 7209.0
## + industry:gender       1     66334 102371236 7209.1
## + occupation:south      1     60065 102377504 7209.1
## + south:smsa            1     59869 102377701 7209.1
## + gender:education      1     51981 102385589 7209.1
## + occupation:gender     1     43170 102394399 7209.2
## + occupation:smsa       1     39144 102398425 7209.2
## + experience:industry   1     34537 102403032 7209.2
## + married:ethnicity     1     31341 102406228 7209.3
## + experience:south      1     30287 102407283 7209.3
## + married:education     1     25224 102412345 7209.3
## + occupation:married    1     19975 102417594 7209.3
## + gender:ethnicity      1     19351 102418218 7209.3
## + education:ethnicity   1     13010 102424559 7209.4
## + experience:married    1     12854 102424716 7209.4
## + experience:smsa       1      7030 102430539 7209.4
## + south:married         1      6446 102431124 7209.4
## + smsa:education        1      4111 102433459 7209.4
## + experience:education  1      3936 102433633 7209.4
## + south:gender          1      1698 102435871 7209.4
## + married:gender        1         1 102437568 7209.4
## + smsa:ethnicity        1         0 102437569 7209.4
## 
## Call:
## lm(formula = YM ~ education + gender + smsa + experience + occupation + 
##     ethnicity + industry + south + married + education:occupation + 
##     education:industry + occupation:ethnicity + smsa:industry + 
##     experience:occupation + education:south + industry:south, 
##     data = mydata2)
## 
## Coefficients:
##            (Intercept)               education                 gender1  
##                  4.433                  28.979                 358.467  
##                  smsa1              experience             occupation1  
##                249.499                   2.762                -692.981  
##             ethnicity1               industry1                  south1  
##                -87.488                -171.323                 372.508  
##               married1   education:occupation1     education:industry1  
##                 97.683                  57.684                  30.091  
## occupation1:ethnicity1         smsa1:industry1  experience:occupation1  
##               -258.882                -150.198                   6.140  
##       education:south1        industry1:south1  
##                -30.238                -155.169
step(modelF, scope=list(lower=model0, upper=modelF), direction="forward")
## Start:  AIC=7239
## YM ~ (experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity)^2
## 
## Call:
## lm(formula = YM ~ (experience + weeks + occupation + industry + 
##     south + smsa + married + gender + union + education + ethnicity)^2, 
##     data = mydata2)
## 
## Coefficients:
##            (Intercept)              experience                   weeks  
##             -7.449e+02               2.186e+01               7.381e+00  
##            occupation1               industry1                  south1  
##             -8.173e+02               2.166e+02               1.003e+03  
##                  smsa1                married1                 gender1  
##              5.009e+02              -1.478e+03               1.602e+03  
##                 union1               education              ethnicity1  
##              1.208e+03               3.464e+01              -6.543e+01  
##       experience:weeks  experience:occupation1    experience:industry1  
##             -4.651e-01               6.081e+00              -3.223e-01  
##      experience:south1        experience:smsa1     experience:married1  
##             -5.065e-01               1.078e+00              -4.836e+00  
##     experience:gender1       experience:union1    experience:education  
##              8.075e+00              -3.395e+00               3.091e-03  
##  experience:ethnicity1       weeks:occupation1         weeks:industry1  
##             -7.168e+00               9.437e+00              -2.022e+00  
##           weeks:south1             weeks:smsa1          weeks:married1  
##             -6.870e+00              -8.398e+00               3.987e+01  
##          weeks:gender1            weeks:union1         weeks:education  
##             -3.526e+01              -1.277e+00               7.587e-01  
##       weeks:ethnicity1   occupation1:industry1      occupation1:south1  
##              1.135e+01               6.487e+00               1.620e+01  
##      occupation1:smsa1    occupation1:married1     occupation1:gender1  
##             -2.445e+01              -9.027e+01               6.534e+01  
##     occupation1:union1   occupation1:education  occupation1:ethnicity1  
##             -1.788e+02               3.817e+01              -1.025e+02  
##       industry1:south1         industry1:smsa1      industry1:married1  
##             -1.994e+02              -1.316e+02               5.612e+01  
##      industry1:gender1        industry1:union1     industry1:education  
##             -1.369e+02              -2.160e+02               1.465e+01  
##   industry1:ethnicity1            south1:smsa1         south1:married1  
##              1.919e+02              -5.662e+01              -3.887e+01  
##         south1:gender1           south1:union1        south1:education  
##              6.854e+01              -8.530e+00              -5.219e+01  
##      south1:ethnicity1          smsa1:married1           smsa1:gender1  
##             -1.411e+01               3.095e+01               1.894e+02  
##           smsa1:union1         smsa1:education        smsa1:ethnicity1  
##             -1.179e+02              -1.850e+00              -9.783e+01  
##       married1:gender1         married1:union1      married1:education  
##             -1.612e+02              -1.814e+02              -8.903e-01  
##    married1:ethnicity1          gender1:union1       gender1:education  
##              3.191e+02               1.514e+02               4.197e+00  
##     gender1:ethnicity1        union1:education       union1:ethnicity1  
##             -5.803e+02              -6.275e+01               1.228e+02  
##   education:ethnicity1  
##             -1.890e+01
#########################################################################
##### Model selection: stepwise algorithms
##### Example 5: first-order models and models with interactions, Backward elimination
#########################################################################

model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~.^2, data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="backward")
## Start:  AIC=7468.15
## YM ~ 1
## 
## Call:
## lm(formula = YM ~ 1, data = mydata2)
## 
## Coefficients:
## (Intercept)  
##        1148
step(modelF, scope=list(lower=model0, upper=modelF), direction="backward")
## Start:  AIC=7239
## YM ~ (experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity)^2
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:education   1         2 91306975 7237.0
## - married:education      1        86 91307059 7237.0
## - occupation:industry    1       618 91307591 7237.0
## - south:ethnicity        1       935 91307908 7237.0
## - south:union            1      1058 91308031 7237.0
## - experience:industry    1      1253 91308226 7237.0
## - gender:education       1      1302 91308275 7237.0
## - smsa:education         1      1486 91308459 7237.0
## - experience:south       1      2308 91309281 7237.0
## - weeks:union            1      3410 91310383 7237.0
## - occupation:south       1      3613 91310586 7237.0
## - smsa:married           1      7733 91314706 7237.1
## - weeks:industry         1      8024 91314997 7237.1
## - occupation:smsa        1      8372 91315345 7237.1
## - occupation:gender      1      9729 91316702 7237.1
## - south:married          1     10650 91317623 7237.1
## - experience:smsa        1     12485 91319458 7237.1
## - married:gender         1     18994 91325967 7237.1
## - smsa:ethnicity         1     20640 91327613 7237.1
## - south:gender           1     21308 91328281 7237.1
## - industry:married       1     24114 91331087 7237.2
## - weeks:education        1     24415 91331388 7237.2
## - occupation:married     1     27245 91334218 7237.2
## - education:ethnicity    1     44180 91351154 7237.3
## - occupation:ethnicity   1     44502 91351475 7237.3
## - industry:gender        1     63323 91370296 7237.4
## - weeks:ethnicity        1     64682 91371655 7237.4
## - south:smsa             1     64812 91371785 7237.4
## - union:ethnicity        1     76462 91383435 7237.5
## - gender:union           1     79645 91386618 7237.5
## - experience:married     1     87133 91394106 7237.6
## - industry:education     1     95204 91402177 7237.6
## - experience:union       1    100023 91406996 7237.7
## - weeks:occupation       1    102123 91409096 7237.7
## - weeks:south            1    106528 91413501 7237.7
## - experience:gender      1    126347 91433320 7237.8
## - smsa:gender            1    144747 91451720 7237.9
## - experience:ethnicity   1    150793 91457767 7238.0
## - weeks:smsa             1    156782 91463756 7238.0
## - married:union          1    190094 91497067 7238.2
## - industry:ethnicity     1    202542 91509515 7238.3
## - married:ethnicity      1    207185 91514158 7238.3
## - experience:weeks       1    241038 91548011 7238.6
## - smsa:union             1    247436 91554409 7238.6
## - experience:occupation  1    279817 91586790 7238.8
## <none>                               91306973 7239.0
## - industry:smsa          1    395448 91702421 7239.6
## - occupation:union       1    411142 91718115 7239.7
## - gender:ethnicity       1    562906 91869879 7240.7
## - occupation:education   1    620025 91926998 7241.0
## - industry:south         1    752501 92059474 7241.9
## - weeks:gender           1    838327 92145300 7242.4
## - industry:union         1    900259 92207232 7242.8
## - south:education        1   1168423 92475396 7244.6
## - union:education        1   1301618 92608591 7245.4
## - weeks:married          1   1505379 92812352 7246.7
## 
## Step:  AIC=7237
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:education + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:education      1        84 91307059 7235.0
## - occupation:industry    1       620 91307596 7235.0
## - south:ethnicity        1       933 91307908 7235.0
## - south:union            1      1057 91308032 7235.0
## - experience:industry    1      1257 91308232 7235.0
## - gender:education       1      1303 91308279 7235.0
## - smsa:education         1      1484 91308459 7235.0
## - experience:south       1      2390 91309365 7235.0
## - weeks:union            1      3421 91310396 7235.0
## - occupation:south       1      3633 91310609 7235.0
## - smsa:married           1      7732 91314707 7235.1
## - weeks:industry         1      8022 91314997 7235.1
## - occupation:smsa        1      8374 91315349 7235.1
## - occupation:gender      1      9727 91316703 7235.1
## - south:married          1     10653 91317628 7235.1
## - experience:smsa        1     12807 91319783 7235.1
## - married:gender         1     19081 91326057 7235.1
## - smsa:ethnicity         1     20653 91327629 7235.1
## - south:gender           1     21384 91328360 7235.1
## - industry:married       1     24263 91331238 7235.2
## - weeks:education        1     24543 91331519 7235.2
## - occupation:married     1     27348 91334324 7235.2
## - education:ethnicity    1     44392 91351368 7235.3
## - occupation:ethnicity   1     44500 91351475 7235.3
## - industry:gender        1     63586 91370561 7235.4
## - south:smsa             1     64843 91371818 7235.4
## - weeks:ethnicity        1     64860 91371835 7235.4
## - union:ethnicity        1     76486 91383462 7235.5
## - gender:union           1     79660 91386636 7235.5
## - experience:married     1     87333 91394308 7235.6
## - industry:education     1     95350 91402326 7235.6
## - experience:union       1    101742 91408718 7235.7
## - weeks:occupation       1    102533 91409509 7235.7
## - weeks:south            1    107228 91414204 7235.7
## - experience:gender      1    127006 91433981 7235.8
## - smsa:gender            1    144756 91451731 7235.9
## - experience:ethnicity   1    150947 91457923 7236.0
## - weeks:smsa             1    156782 91463758 7236.0
## - married:union          1    190407 91497382 7236.2
## - industry:ethnicity     1    202927 91509903 7236.3
## - married:ethnicity      1    207392 91514367 7236.3
## - experience:weeks       1    241189 91548164 7236.6
## - smsa:union             1    247669 91554645 7236.6
## <none>                               91306975 7237.0
## - industry:smsa          1    397490 91704466 7237.6
## - experience:occupation  1    410984 91717960 7237.7
## - occupation:union       1    422118 91729093 7237.7
## - gender:ethnicity       1    563265 91870240 7238.7
## - occupation:education   1    621310 91928286 7239.0
## - industry:south         1    754162 92061138 7239.9
## - weeks:gender           1    843006 92149982 7240.5
## - industry:union         1    904630 92211605 7240.9
## - south:education        1   1180347 92487322 7242.6
## - union:education        1   1318095 92625071 7243.5
## - weeks:married          1   1507936 92814912 7244.7
## 
## Step:  AIC=7235
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:industry    1       655 91307714 7233.0
## - south:ethnicity        1       938 91307997 7233.0
## - south:union            1      1043 91308102 7233.0
## - experience:industry    1      1318 91308377 7233.0
## - smsa:education         1      1460 91308519 7233.0
## - gender:education       1      2086 91309145 7233.0
## - experience:south       1      2376 91309435 7233.0
## - weeks:union            1      3408 91310467 7233.0
## - occupation:south       1      3698 91310757 7233.0
## - smsa:married           1      7696 91314755 7233.1
## - weeks:industry         1      8185 91315244 7233.1
## - occupation:smsa        1      8455 91315514 7233.1
## - south:married          1     10656 91317715 7233.1
## - experience:smsa        1     12992 91320051 7233.1
## - occupation:gender      1     15753 91322812 7233.1
## - married:gender         1     18998 91326057 7233.1
## - smsa:ethnicity         1     20570 91327629 7233.1
## - south:gender           1     21398 91328457 7233.1
## - weeks:education        1     24626 91331685 7233.2
## - industry:married       1     26885 91333944 7233.2
## - education:ethnicity    1     44479 91351538 7233.3
## - occupation:ethnicity   1     44751 91351810 7233.3
## - occupation:married     1     60906 91367965 7233.4
## - south:smsa             1     64928 91371987 7233.4
## - industry:gender        1     66135 91373194 7233.4
## - weeks:ethnicity        1     66321 91373380 7233.4
## - union:ethnicity        1     76698 91383757 7233.5
## - gender:union           1     79751 91386810 7233.5
## - experience:married     1     89098 91396157 7233.6
## - industry:education     1     95307 91402366 7233.6
## - experience:union       1    101844 91408903 7233.7
## - weeks:occupation       1    102452 91409511 7233.7
## - weeks:south            1    107633 91414692 7233.7
## - experience:gender      1    127691 91434750 7233.8
## - smsa:gender            1    144694 91451753 7233.9
## - experience:ethnicity   1    151353 91458412 7234.0
## - weeks:smsa             1    156729 91463788 7234.0
## - married:union          1    190406 91497465 7234.2
## - industry:ethnicity     1    202860 91509919 7234.3
## - married:ethnicity      1    236420 91543479 7234.5
## - experience:weeks       1    242203 91549262 7234.6
## - smsa:union             1    247678 91554737 7234.6
## <none>                               91307059 7235.0
## - industry:smsa          1    397407 91704467 7235.6
## - experience:occupation  1    410932 91717991 7235.7
## - occupation:union       1    422222 91729281 7235.7
## - gender:ethnicity       1    621670 91928729 7237.0
## - occupation:education   1    621762 91928821 7237.0
## - industry:south         1    755862 92062921 7237.9
## - weeks:gender           1    843241 92150300 7238.5
## - industry:union         1    904547 92211606 7238.9
## - south:education        1   1180683 92487742 7240.6
## - union:education        1   1319487 92626546 7241.5
## - weeks:married          1   1514222 92821281 7242.8
## 
## Step:  AIC=7233
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + south:ethnicity + smsa:married + smsa:gender + 
##     smsa:union + smsa:education + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:education + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:ethnicity        1       894 91308609 7231.0
## - south:union            1      1100 91308815 7231.0
## - experience:industry    1      1131 91308845 7231.0
## - smsa:education         1      1302 91309017 7231.0
## - gender:education       1      1747 91309461 7231.0
## - experience:south       1      2243 91309958 7231.0
## - weeks:union            1      3477 91311191 7231.0
## - occupation:south       1      3543 91311257 7231.0
## - smsa:married           1      7559 91315274 7231.1
## - weeks:industry         1      8188 91315903 7231.1
## - occupation:smsa        1      8340 91316054 7231.1
## - south:married          1     10496 91318211 7231.1
## - experience:smsa        1     13368 91321082 7231.1
## - occupation:gender      1     16780 91324494 7231.1
## - married:gender         1     19004 91326719 7231.1
## - smsa:ethnicity         1     20751 91328465 7231.1
## - south:gender           1     21158 91328872 7231.1
## - weeks:education        1     25791 91333505 7231.2
## - industry:married       1     26940 91334654 7231.2
## - occupation:ethnicity   1     44209 91351924 7231.3
## - education:ethnicity    1     45216 91352931 7231.3
## - occupation:married     1     60251 91367966 7231.4
## - south:smsa             1     64518 91372232 7231.4
## - industry:gender        1     65577 91373291 7231.4
## - weeks:ethnicity        1     67968 91375683 7231.4
## - union:ethnicity        1     77438 91385153 7231.5
## - gender:union           1     79225 91386939 7231.5
## - experience:married     1     89676 91397391 7231.6
## - weeks:occupation       1    101939 91409653 7231.7
## - experience:union       1    102977 91410692 7231.7
## - weeks:south            1    108557 91416272 7231.7
## - experience:gender      1    128598 91436312 7231.8
## - industry:education     1    143217 91450931 7231.9
## - smsa:gender            1    144843 91452557 7231.9
## - experience:ethnicity   1    152497 91460211 7232.0
## - weeks:smsa             1    156504 91464219 7232.0
## - married:union          1    189990 91497704 7232.2
## - industry:ethnicity     1    203710 91511424 7232.3
## - married:ethnicity      1    237397 91545111 7232.5
## - experience:weeks       1    243623 91551337 7232.6
## - smsa:union             1    248743 91556458 7232.6
## <none>                               91307714 7233.0
## - industry:smsa          1    397791 91705505 7233.6
## - experience:occupation  1    412653 91720368 7233.7
## - occupation:union       1    426855 91734570 7233.8
## - occupation:education   1    621645 91929359 7235.0
## - gender:ethnicity       1    626490 91934205 7235.1
## - industry:south         1    758603 92066317 7235.9
## - weeks:gender           1    842590 92150305 7236.5
## - industry:union         1   1034938 92342652 7237.7
## - south:education        1   1181633 92489348 7238.7
## - union:education        1   1332643 92640357 7239.6
## - weeks:married          1   1513613 92821327 7240.8
## 
## Step:  AIC=7231.01
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + smsa:married + smsa:gender + smsa:union + 
##     smsa:education + smsa:ethnicity + married:gender + married:union + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:union            1      1105 91309714 7229.0
## - experience:industry    1      1117 91309726 7229.0
## - smsa:education         1      1252 91309861 7229.0
## - gender:education       1      1727 91310335 7229.0
## - experience:south       1      2552 91311161 7229.0
## - weeks:union            1      3354 91311963 7229.0
## - occupation:south       1      3740 91312349 7229.0
## - smsa:married           1      7467 91316076 7229.1
## - weeks:industry         1      7787 91316396 7229.1
## - occupation:smsa        1      8195 91316804 7229.1
## - south:married          1     10035 91318644 7229.1
## - experience:smsa        1     13158 91321767 7229.1
## - occupation:gender      1     16014 91324622 7229.1
## - married:gender         1     19165 91327774 7229.1
## - south:gender           1     22202 91330811 7229.2
## - smsa:ethnicity         1     22937 91331546 7229.2
## - industry:married       1     26432 91335041 7229.2
## - weeks:education        1     27066 91335675 7229.2
## - occupation:ethnicity   1     45927 91354535 7229.3
## - education:ethnicity    1     46242 91354851 7229.3
## - occupation:married     1     59706 91368315 7229.4
## - industry:gender        1     66906 91375515 7229.4
## - weeks:ethnicity        1     69598 91378207 7229.5
## - south:smsa             1     72426 91381035 7229.5
## - gender:union           1     78677 91387286 7229.5
## - union:ethnicity        1     89603 91398212 7229.6
## - experience:married     1     90060 91398668 7229.6
## - weeks:occupation       1    101177 91409786 7229.7
## - experience:union       1    102250 91410859 7229.7
## - weeks:south            1    107679 91416288 7229.7
## - experience:gender      1    128151 91436760 7229.8
## - industry:education     1    144749 91453358 7230.0
## - smsa:gender            1    146220 91454828 7230.0
## - weeks:smsa             1    156815 91465423 7230.0
## - experience:ethnicity   1    162705 91471314 7230.1
## - married:union          1    192822 91501431 7230.3
## - industry:ethnicity     1    204624 91513233 7230.3
## - experience:weeks       1    243385 91551994 7230.6
## - smsa:union             1    248153 91556762 7230.6
## - married:ethnicity      1    255771 91564380 7230.7
## <none>                               91308609 7231.0
## - industry:smsa          1    400501 91709110 7231.6
## - experience:occupation  1    411762 91720371 7231.7
## - occupation:union       1    437048 91745657 7231.9
## - occupation:education   1    623737 91932346 7233.1
## - gender:ethnicity       1    634497 91943106 7233.1
## - industry:south         1    758484 92067092 7233.9
## - weeks:gender           1    896795 92205403 7234.8
## - industry:union         1   1034530 92343138 7235.7
## - south:education        1   1182880 92491489 7236.7
## - union:education        1   1332718 92641327 7237.6
## - weeks:married          1   1570636 92879244 7239.2
## 
## Step:  AIC=7229.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:industry    1      1087 91310801 7227.0
## - smsa:education         1      1422 91311135 7227.0
## - gender:education       1      1727 91311440 7227.0
## - experience:south       1      2304 91312018 7227.0
## - weeks:union            1      3183 91312897 7227.0
## - occupation:south       1      5314 91315028 7227.1
## - occupation:smsa        1      7325 91317038 7227.1
## - weeks:industry         1      7561 91317274 7227.1
## - smsa:married           1      7616 91317330 7227.1
## - south:married          1     10679 91320393 7227.1
## - experience:smsa        1     13141 91322854 7227.1
## - occupation:gender      1     15627 91325340 7227.1
## - married:gender         1     18935 91328649 7227.1
## - south:gender           1     21354 91331067 7227.2
## - smsa:ethnicity         1     22401 91332115 7227.2
## - industry:married       1     25952 91335665 7227.2
## - weeks:education        1     27745 91337458 7227.2
## - education:ethnicity    1     47106 91356819 7227.3
## - occupation:ethnicity   1     48537 91358251 7227.3
## - occupation:married     1     59072 91368786 7227.4
## - industry:gender        1     66784 91376498 7227.5
## - weeks:ethnicity        1     70281 91379994 7227.5
## - south:smsa             1     74168 91383881 7227.5
## - gender:union           1     77574 91387288 7227.5
## - union:ethnicity        1     88632 91398345 7227.6
## - experience:married     1     92173 91401886 7227.6
## - weeks:occupation       1    100385 91410098 7227.7
## - experience:union       1    101329 91411043 7227.7
## - weeks:south            1    107123 91416836 7227.7
## - experience:gender      1    128486 91438199 7227.9
## - industry:education     1    143665 91453378 7228.0
## - smsa:gender            1    146103 91455816 7228.0
## - weeks:smsa             1    158735 91468448 7228.1
## - experience:ethnicity   1    162464 91472178 7228.1
## - married:union          1    192607 91502321 7228.3
## - industry:ethnicity     1    204550 91514263 7228.3
## - experience:weeks       1    243451 91553164 7228.6
## - smsa:union             1    252834 91562548 7228.7
## - married:ethnicity      1    258376 91568089 7228.7
## <none>                               91309714 7229.0
## - industry:smsa          1    407013 91716727 7229.7
## - experience:occupation  1    422158 91731872 7229.8
## - occupation:union       1    447226 91756939 7229.9
## - occupation:education   1    630284 91939997 7231.1
## - gender:ethnicity       1    634198 91943911 7231.1
## - industry:south         1    766957 92076671 7232.0
## - weeks:gender           1    898271 92207985 7232.8
## - industry:union         1   1033427 92343140 7233.7
## - south:education        1   1190365 92500078 7234.7
## - union:education        1   1380414 92690128 7235.9
## - weeks:married          1   1570625 92880339 7237.2
## 
## Step:  AIC=7227.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:education         1      1342 91312143 7225.0
## - gender:education       1      1666 91312467 7225.0
## - experience:south       1      1838 91312638 7225.0
## - weeks:union            1      3087 91313888 7225.0
## - occupation:south       1      5086 91315886 7225.1
## - weeks:industry         1      7030 91317830 7225.1
## - smsa:married           1      7557 91318358 7225.1
## - occupation:smsa        1      7717 91318518 7225.1
## - south:married          1     11108 91321909 7225.1
## - experience:smsa        1     13292 91324093 7225.1
## - occupation:gender      1     15599 91326400 7225.1
## - married:gender         1     19115 91329915 7225.1
## - south:gender           1     21809 91332609 7225.2
## - smsa:ethnicity         1     22234 91333034 7225.2
## - industry:married       1     25124 91335925 7225.2
## - weeks:education        1     27583 91338384 7225.2
## - education:ethnicity    1     47495 91358296 7225.3
## - occupation:ethnicity   1     48161 91358961 7225.3
## - occupation:married     1     60106 91370907 7225.4
## - industry:gender        1     66629 91377429 7225.5
## - weeks:ethnicity        1     69830 91380631 7225.5
## - south:smsa             1     74029 91384830 7225.5
## - gender:union           1     78783 91389583 7225.5
## - union:ethnicity        1     87983 91398784 7225.6
## - experience:married     1     92371 91403171 7225.6
## - weeks:occupation       1    101606 91412407 7225.7
## - experience:union       1    102933 91413734 7225.7
## - weeks:south            1    106514 91417314 7225.7
## - experience:gender      1    127800 91438600 7225.9
## - smsa:gender            1    146555 91457356 7226.0
## - industry:education     1    158263 91469064 7226.1
## - weeks:smsa             1    159069 91469869 7226.1
## - experience:ethnicity   1    161453 91472253 7226.1
## - married:union          1    194039 91504839 7226.3
## - industry:ethnicity     1    204282 91515082 7226.4
## - experience:weeks       1    242367 91553167 7226.6
## - smsa:union             1    251810 91562611 7226.7
## - married:ethnicity      1    260542 91571342 7226.7
## <none>                               91310801 7227.0
## - industry:smsa          1    421468 91732269 7227.8
## - experience:occupation  1    436887 91747688 7227.9
## - occupation:union       1    446139 91756939 7227.9
## - occupation:education   1    629812 91940613 7229.1
## - gender:ethnicity       1    636293 91947094 7229.2
## - industry:south         1    768557 92079357 7230.0
## - weeks:gender           1    898368 92209169 7230.9
## - industry:union         1   1037784 92348585 7231.7
## - south:education        1   1189279 92500079 7232.7
## - union:education        1   1385837 92696637 7234.0
## - weeks:married          1   1572634 92883435 7235.2
## 
## Step:  AIC=7225.03
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:south       1      1717 91313860 7223.0
## - gender:education       1      1905 91314048 7223.0
## - weeks:union            1      3051 91315194 7223.1
## - occupation:south       1      4334 91316477 7223.1
## - weeks:industry         1      7045 91319187 7223.1
## - smsa:married           1      7313 91319455 7223.1
## - south:married          1     11262 91323404 7223.1
## - occupation:gender      1     15426 91327569 7223.1
## - experience:smsa        1     16694 91328837 7223.1
## - occupation:smsa        1     17469 91329612 7223.1
## - married:gender         1     18927 91331070 7223.2
## - smsa:ethnicity         1     21150 91333292 7223.2
## - south:gender           1     21720 91333863 7223.2
## - industry:married       1     24906 91337049 7223.2
## - weeks:education        1     27314 91339457 7223.2
## - occupation:ethnicity   1     47067 91359210 7223.3
## - education:ethnicity    1     53868 91366011 7223.4
## - occupation:married     1     60788 91372931 7223.4
## - industry:gender        1     66322 91378465 7223.5
## - weeks:ethnicity        1     69706 91381849 7223.5
## - south:smsa             1     72725 91384868 7223.5
## - gender:union           1     77765 91389908 7223.5
## - union:ethnicity        1     87305 91399448 7223.6
## - experience:married     1     91564 91403707 7223.6
## - weeks:occupation       1    101710 91413853 7223.7
## - experience:union       1    103284 91415427 7223.7
## - weeks:south            1    105397 91417540 7223.7
## - experience:gender      1    127824 91439967 7223.9
## - smsa:gender            1    145532 91457675 7224.0
## - industry:education     1    157406 91469549 7224.1
## - weeks:smsa             1    157727 91469870 7224.1
## - experience:ethnicity   1    163042 91475185 7224.1
## - married:union          1    193490 91505633 7224.3
## - industry:ethnicity     1    204054 91516197 7224.4
## - experience:weeks       1    242817 91554960 7224.6
## - smsa:union             1    250961 91563104 7224.7
## - married:ethnicity      1    262066 91574209 7224.7
## <none>                               91312143 7225.0
## - industry:smsa          1    423467 91735609 7225.8
## - experience:occupation  1    435581 91747724 7225.9
## - occupation:union       1    444852 91756995 7225.9
## - gender:ethnicity       1    636551 91948694 7227.2
## - occupation:education   1    652919 91965062 7227.3
## - industry:south         1    776195 92088338 7228.1
## - weeks:gender           1    897093 92209236 7228.9
## - industry:union         1   1036806 92348949 7229.8
## - south:education        1   1239977 92552120 7231.1
## - union:education        1   1397651 92709794 7232.1
## - weeks:married          1   1571293 92883435 7233.2
## 
## Step:  AIC=7223.04
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:education       1      1745 91315605 7221.1
## - weeks:union            1      2552 91316412 7221.1
## - occupation:south       1      4081 91317941 7221.1
## - weeks:industry         1      7273 91321133 7221.1
## - smsa:married           1      7344 91321204 7221.1
## - south:married          1     12279 91326139 7221.1
## - occupation:gender      1     15768 91329628 7221.1
## - occupation:smsa        1     17485 91331344 7221.2
## - married:gender         1     17811 91331670 7221.2
## - experience:smsa        1     19356 91333216 7221.2
## - south:gender           1     21269 91335128 7221.2
## - smsa:ethnicity         1     21986 91335846 7221.2
## - industry:married       1     24403 91338263 7221.2
## - weeks:education        1     28395 91342254 7221.2
## - occupation:ethnicity   1     46884 91360744 7221.4
## - education:ethnicity    1     55145 91369005 7221.4
## - occupation:married     1     62542 91376402 7221.5
## - industry:gender        1     65614 91379473 7221.5
## - weeks:ethnicity        1     69275 91383135 7221.5
## - south:smsa             1     74376 91388236 7221.5
## - gender:union           1     78727 91392587 7221.6
## - experience:married     1     90246 91404106 7221.6
## - union:ethnicity        1     91101 91404961 7221.6
## - weeks:occupation       1    101362 91415222 7221.7
## - experience:union       1    102218 91416078 7221.7
## - weeks:south            1    104300 91418160 7221.7
## - experience:gender      1    126269 91440129 7221.9
## - smsa:gender            1    145837 91459697 7222.0
## - industry:education     1    156397 91470257 7222.1
## - weeks:smsa             1    157214 91471074 7222.1
## - experience:ethnicity   1    179239 91493099 7222.2
## - married:union          1    199058 91512918 7222.3
## - industry:ethnicity     1    204337 91518197 7222.4
## - experience:weeks       1    241536 91555396 7222.6
## - smsa:union             1    252694 91566554 7222.7
## - married:ethnicity      1    261860 91575719 7222.7
## <none>                               91313860 7223.0
## - industry:smsa          1    423650 91737509 7223.8
## - experience:occupation  1    440113 91753972 7223.9
## - occupation:union       1    445680 91759540 7223.9
## - gender:ethnicity       1    638664 91952524 7225.2
## - occupation:education   1    655286 91969146 7225.3
## - industry:south         1    775025 92088885 7226.1
## - weeks:gender           1    895377 92209236 7226.9
## - industry:union         1   1035201 92349061 7227.8
## - south:education        1   1304488 92618348 7229.5
## - union:education        1   1403408 92717268 7230.1
## - weeks:married          1   1571747 92885606 7231.2
## 
## Step:  AIC=7221.06
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:union            1      2668 91318272 7219.1
## - occupation:south       1      4367 91319972 7219.1
## - weeks:industry         1      6825 91322429 7219.1
## - smsa:married           1      7490 91323095 7219.1
## - south:married          1     12573 91328178 7219.1
## - married:gender         1     16938 91332542 7219.2
## - occupation:smsa        1     16950 91332555 7219.2
## - experience:smsa        1     19484 91335088 7219.2
## - smsa:ethnicity         1     21367 91336972 7219.2
## - south:gender           1     21664 91337269 7219.2
## - occupation:gender      1     24385 91339990 7219.2
## - industry:married       1     24408 91340012 7219.2
## - weeks:education        1     30894 91346498 7219.3
## - occupation:ethnicity   1     45308 91360913 7219.4
## - education:ethnicity    1     59815 91375420 7219.4
## - occupation:married     1     62958 91378563 7219.5
## - industry:gender        1     64608 91380213 7219.5
## - weeks:ethnicity        1     69280 91384884 7219.5
## - south:smsa             1     74123 91389728 7219.5
## - gender:union           1     81714 91397318 7219.6
## - experience:married     1     90675 91406280 7219.6
## - union:ethnicity        1     91061 91406666 7219.6
## - weeks:occupation       1    100261 91415865 7219.7
## - experience:union       1    103019 91418623 7219.7
## - weeks:south            1    104522 91420126 7219.7
## - experience:gender      1    125629 91441233 7219.9
## - smsa:gender            1    148130 91463734 7220.0
## - weeks:smsa             1    156892 91472496 7220.1
## - industry:education     1    166052 91481657 7220.1
## - experience:ethnicity   1    181902 91497507 7220.2
## - married:union          1    199765 91515370 7220.4
## - industry:ethnicity     1    202699 91518303 7220.4
## - experience:weeks       1    247836 91563441 7220.7
## - smsa:union             1    250959 91566563 7220.7
## - married:ethnicity      1    272586 91588190 7220.8
## <none>                               91315605 7221.1
## - industry:smsa          1    425397 91741002 7221.8
## - experience:occupation  1    440749 91756353 7221.9
## - occupation:union       1    451247 91766851 7222.0
## - occupation:education   1    654644 91970249 7223.3
## - gender:ethnicity       1    668144 91983749 7223.4
## - industry:south         1    773281 92088886 7224.1
## - weeks:gender           1    897886 92213491 7224.9
## - industry:union         1   1034299 92349904 7225.8
## - south:education        1   1307257 92622861 7227.5
## - union:education        1   1402900 92718505 7228.1
## - weeks:married          1   1571155 92886760 7229.2
## 
## Step:  AIC=7219.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:south       1      3893 91322166 7217.1
## - weeks:industry         1      6916 91325189 7217.1
## - smsa:married           1      7675 91325947 7217.1
## - south:married          1     12776 91331048 7217.2
## - married:gender         1     17144 91335417 7217.2
## - experience:smsa        1     17755 91336028 7217.2
## - occupation:smsa        1     18227 91336499 7217.2
## - smsa:ethnicity         1     21099 91339371 7217.2
## - south:gender           1     21461 91339733 7217.2
## - occupation:gender      1     24316 91342588 7217.2
## - industry:married       1     25173 91343445 7217.2
## - weeks:education        1     32162 91350434 7217.3
## - occupation:ethnicity   1     45552 91363825 7217.4
## - education:ethnicity    1     59925 91378197 7217.5
## - industry:gender        1     64148 91382421 7217.5
## - occupation:married     1     64380 91382652 7217.5
## - weeks:ethnicity        1     74558 91392830 7217.6
## - south:smsa             1     75658 91393930 7217.6
## - gender:union           1     79966 91398238 7217.6
## - experience:married     1     90317 91408589 7217.7
## - union:ethnicity        1     90694 91408967 7217.7
## - experience:union       1    100497 91418770 7217.7
## - weeks:south            1    101897 91420169 7217.7
## - weeks:occupation       1    116904 91435176 7217.8
## - experience:gender      1    124392 91442664 7217.9
## - smsa:gender            1    148530 91466802 7218.0
## - industry:education     1    165536 91483808 7218.2
## - experience:ethnicity   1    181221 91499493 7218.3
## - weeks:smsa             1    200247 91518520 7218.4
## - industry:ethnicity     1    200951 91519223 7218.4
## - married:union          1    203103 91521376 7218.4
## - experience:weeks       1    245208 91563481 7218.7
## - smsa:union             1    271016 91589289 7218.8
## - married:ethnicity      1    273184 91591456 7218.9
## <none>                               91318272 7219.1
## - industry:smsa          1    422790 91741062 7219.8
## - experience:occupation  1    443420 91761692 7220.0
## - occupation:union       1    448761 91767034 7220.0
## - occupation:education   1    660097 91978370 7221.4
## - gender:ethnicity       1    667219 91985491 7221.4
## - industry:south         1    772424 92090696 7222.1
## - weeks:gender           1    900033 92218305 7222.9
## - industry:union         1   1033007 92351279 7223.8
## - south:education        1   1307956 92626228 7225.5
## - union:education        1   1408689 92726961 7226.2
## - weeks:married          1   1586335 92904608 7227.3
## 
## Step:  AIC=7217.1
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:married           1      7707 91329872 7215.1
## - weeks:industry         1      7809 91329974 7215.1
## - south:married          1     12580 91334746 7215.2
## - married:gender         1     17096 91339261 7215.2
## - experience:smsa        1     17273 91339439 7215.2
## - occupation:smsa        1     20465 91342631 7215.2
## - south:gender           1     20777 91342942 7215.2
## - smsa:ethnicity         1     22236 91344402 7215.2
## - occupation:gender      1     24075 91346241 7215.3
## - industry:married       1     24991 91347157 7215.3
## - weeks:education        1     33460 91355626 7215.3
## - occupation:ethnicity   1     42773 91364938 7215.4
## - education:ethnicity    1     60640 91382806 7215.5
## - occupation:married     1     63679 91385845 7215.5
## - industry:gender        1     63934 91386100 7215.5
## - south:smsa             1     72845 91395011 7215.6
## - weeks:ethnicity        1     77439 91399605 7215.6
## - gender:union           1     79870 91402036 7215.6
## - experience:married     1     89189 91411354 7215.7
## - union:ethnicity        1     95765 91417931 7215.7
## - experience:union       1    101071 91423237 7215.8
## - weeks:south            1    101856 91424022 7215.8
## - weeks:occupation       1    114285 91436450 7215.8
## - experience:gender      1    123614 91445779 7215.9
## - smsa:gender            1    149012 91471178 7216.1
## - industry:education     1    162028 91484194 7216.2
## - experience:ethnicity   1    180620 91502786 7216.3
## - weeks:smsa             1    200350 91522515 7216.4
## - married:union          1    202554 91524720 7216.4
## - industry:ethnicity     1    204837 91527003 7216.4
## - experience:weeks       1    243664 91565830 7216.7
## - married:ethnicity      1    269662 91591827 7216.9
## - smsa:union             1    282666 91604831 7216.9
## <none>                               91322166 7217.1
## - industry:smsa          1    424610 91746776 7217.9
## - experience:occupation  1    442474 91764640 7218.0
## - occupation:union       1    473189 91795355 7218.2
## - occupation:education   1    657721 91979886 7219.4
## - gender:ethnicity       1    664937 91987103 7219.4
## - industry:south         1    810849 92133015 7220.4
## - weeks:gender           1    898963 92221129 7220.9
## - industry:union         1   1041789 92363954 7221.8
## - union:education        1   1413780 92735945 7224.2
## - weeks:married          1   1586977 92909143 7225.3
## - south:education        1   1743189 93065355 7226.3
## 
## Step:  AIC=7215.15
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:industry         1      6887 91336760 7213.2
## - south:married          1     16580 91346452 7213.3
## - occupation:smsa        1     19084 91348957 7213.3
## - married:gender         1     19348 91349220 7213.3
## - experience:smsa        1     19445 91349317 7213.3
## - occupation:gender      1     20812 91350684 7213.3
## - industry:married       1     21738 91351611 7213.3
## - smsa:ethnicity         1     23180 91353052 7213.3
## - south:gender           1     24786 91354659 7213.3
## - weeks:education        1     34402 91364275 7213.4
## - occupation:ethnicity   1     45208 91375080 7213.4
## - occupation:married     1     57552 91387424 7213.5
## - industry:gender        1     61581 91391454 7213.6
## - education:ethnicity    1     62296 91392168 7213.6
## - south:smsa             1     75320 91405193 7213.6
## - weeks:ethnicity        1     75641 91405513 7213.6
## - gender:union           1     78207 91408080 7213.7
## - experience:married     1     90993 91420865 7213.7
## - union:ethnicity        1     93786 91423658 7213.8
## - weeks:south            1     97734 91427607 7213.8
## - experience:union       1    101107 91430979 7213.8
## - weeks:occupation       1    115334 91445207 7213.9
## - experience:gender      1    125634 91455506 7214.0
## - industry:education     1    160208 91490081 7214.2
## - experience:ethnicity   1    182456 91512329 7214.3
## - weeks:smsa             1    196729 91526602 7214.4
## - married:union          1    199085 91528957 7214.4
## - industry:ethnicity     1    202175 91532047 7214.5
## - experience:weeks       1    240350 91570222 7214.7
## - smsa:union             1    277162 91607034 7215.0
## - married:ethnicity      1    280645 91610518 7215.0
## <none>                               91329872 7215.1
## - smsa:gender            1    334544 91664417 7215.3
## - industry:smsa          1    429397 91759269 7215.9
## - experience:occupation  1    441514 91771387 7216.0
## - occupation:union       1    474188 91804060 7216.2
## - occupation:education   1    661204 91991077 7217.4
## - gender:ethnicity       1    675499 92005371 7217.5
## - industry:south         1    835478 92165351 7218.6
## - weeks:gender           1    922055 92251927 7219.1
## - industry:union         1   1034239 92364112 7219.8
## - union:education        1   1420257 92750129 7222.3
## - weeks:married          1   1629901 92959773 7223.7
## - south:education        1   1740631 93070503 7224.4
## 
## Step:  AIC=7213.19
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:married          1     18218 91354977 7211.3
## - occupation:gender      1     19000 91355759 7211.3
## - experience:smsa        1     19446 91356206 7211.3
## - occupation:smsa        1     19826 91356585 7211.3
## - married:gender         1     20235 91356994 7211.3
## - smsa:ethnicity         1     21306 91358066 7211.3
## - industry:married       1     21721 91358480 7211.3
## - south:gender           1     25794 91362554 7211.4
## - weeks:education        1     43083 91379842 7211.5
## - occupation:ethnicity   1     47833 91384593 7211.5
## - occupation:married     1     58036 91394796 7211.6
## - education:ethnicity    1     61386 91398146 7211.6
## - industry:gender        1     66112 91402871 7211.6
## - south:smsa             1     75172 91411932 7211.7
## - gender:union           1     77329 91414089 7211.7
## - weeks:ethnicity        1     92263 91429022 7211.8
## - experience:married     1     93796 91430555 7211.8
## - union:ethnicity        1     94576 91431335 7211.8
## - experience:union       1    102818 91439578 7211.9
## - weeks:south            1    109013 91445772 7211.9
## - experience:gender      1    130727 91467487 7212.0
## - weeks:occupation       1    141885 91478644 7212.1
## - industry:education     1    160715 91497474 7212.2
## - experience:ethnicity   1    184771 91521530 7212.4
## - married:union          1    197558 91534318 7212.5
## - industry:ethnicity     1    199423 91536182 7212.5
## - weeks:smsa             1    239991 91576750 7212.8
## - experience:weeks       1    255997 91592757 7212.9
## - smsa:union             1    275402 91612162 7213.0
## - married:ethnicity      1    288277 91625037 7213.1
## <none>                               91336760 7213.2
## - smsa:gender            1    340671 91677431 7213.4
## - industry:smsa          1    434038 91770797 7214.0
## - experience:occupation  1    441980 91778740 7214.1
## - occupation:union       1    468187 91804946 7214.2
## - occupation:education   1    655228 91991988 7215.4
## - gender:ethnicity       1    688291 92025051 7215.7
## - industry:south         1    828621 92165381 7216.6
## - industry:union         1   1030914 92367673 7217.9
## - weeks:gender           1   1037751 92374511 7217.9
## - union:education        1   1425423 92762183 7220.4
## - weeks:married          1   1681076 93017835 7222.0
## - south:education        1   1737991 93074750 7222.4
## 
## Step:  AIC=7211.31
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:gender + 
##     south:education + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:gender           1      8466 91363443 7209.4
## - married:gender         1     14175 91369152 7209.4
## - occupation:smsa        1     17451 91372428 7209.4
## - occupation:gender      1     17785 91372762 7209.4
## - experience:smsa        1     21326 91376304 7209.5
## - industry:married       1     23414 91378392 7209.5
## - smsa:ethnicity         1     23464 91378441 7209.5
## - weeks:education        1     40262 91395239 7209.6
## - occupation:ethnicity   1     44127 91399104 7209.6
## - occupation:married     1     53796 91408773 7209.7
## - education:ethnicity    1     63419 91418397 7209.7
## - gender:union           1     65883 91420860 7209.7
## - industry:gender        1     67062 91422040 7209.7
## - south:smsa             1     68430 91423407 7209.8
## - union:ethnicity        1    100691 91455668 7210.0
## - weeks:ethnicity        1    104000 91458977 7210.0
## - experience:married     1    107638 91462615 7210.0
## - experience:union       1    111593 91466570 7210.0
## - weeks:south            1    119708 91474685 7210.1
## - experience:gender      1    144513 91499490 7210.3
## - weeks:occupation       1    151510 91506487 7210.3
## - industry:education     1    152457 91507434 7210.3
## - married:union          1    179368 91534346 7210.5
## - experience:ethnicity   1    186211 91541188 7210.5
## - industry:ethnicity     1    195886 91550864 7210.6
## - weeks:smsa             1    247851 91602828 7210.9
## - smsa:union             1    262745 91617722 7211.0
## - experience:weeks       1    265322 91620300 7211.0
## - married:ethnicity      1    270866 91625844 7211.1
## <none>                               91354977 7211.3
## - smsa:gender            1    336089 91691066 7211.5
## - industry:smsa          1    422427 91777404 7212.1
## - experience:occupation  1    433262 91788239 7212.1
## - occupation:union       1    466110 91821087 7212.3
## - occupation:education   1    664273 92019250 7213.6
## - gender:ethnicity       1    671907 92026885 7213.7
## - industry:south         1    836437 92191414 7214.7
## - weeks:gender           1   1032352 92387329 7216.0
## - industry:union         1   1037249 92392226 7216.0
## - union:education        1   1421036 92776014 7218.5
## - weeks:married          1   1691530 93046507 7220.2
## - south:education        1   1733563 93088540 7220.5
## 
## Step:  AIC=7209.37
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:gender         1     11110 91374554 7207.4
## - occupation:smsa        1     17997 91381441 7207.5
## - experience:smsa        1     20351 91383795 7207.5
## - occupation:gender      1     21238 91384681 7207.5
## - industry:married       1     23339 91386782 7207.5
## - smsa:ethnicity         1     23903 91387346 7207.5
## - weeks:education        1     39669 91403112 7207.6
## - occupation:ethnicity   1     44510 91407954 7207.7
## - occupation:married     1     55041 91418484 7207.7
## - gender:union           1     58337 91421780 7207.7
## - education:ethnicity    1     64554 91427998 7207.8
## - industry:gender        1     65162 91428605 7207.8
## - south:smsa             1     76986 91440430 7207.9
## - union:ethnicity        1    101496 91464939 7208.0
## - weeks:ethnicity        1    107353 91470797 7208.1
## - experience:union       1    109257 91472700 7208.1
## - experience:married     1    109660 91473103 7208.1
## - weeks:south            1    115876 91479319 7208.1
## - experience:gender      1    140512 91503955 7208.3
## - weeks:occupation       1    149829 91513273 7208.3
## - industry:education     1    158477 91521920 7208.4
## - married:union          1    180649 91544092 7208.5
## - experience:ethnicity   1    188171 91551615 7208.6
## - industry:ethnicity     1    199309 91562753 7208.7
## - weeks:smsa             1    249759 91613202 7209.0
## - married:ethnicity      1    266563 91630007 7209.1
## - experience:weeks       1    267124 91630567 7209.1
## - smsa:union             1    272171 91635614 7209.1
## <none>                               91363443 7209.4
## - smsa:gender            1    327972 91691415 7209.5
## - industry:smsa          1    421192 91784636 7210.1
## - experience:occupation  1    440106 91803549 7210.2
## - occupation:union       1    468761 91832204 7210.4
## - gender:ethnicity       1    668073 92031516 7211.7
## - occupation:education   1    671651 92035095 7211.7
## - industry:south         1    831462 92194905 7212.8
## - industry:union         1   1029584 92393027 7214.0
## - weeks:gender           1   1049011 92412455 7214.2
## - union:education        1   1414951 92778395 7216.5
## - weeks:married          1   1687582 93051025 7218.3
## - south:education        1   1725340 93088783 7218.5
## 
## Step:  AIC=7207.44
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:union + 
##     married:ethnicity + gender:union + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:gender      1     17190 91391744 7205.6
## - occupation:smsa        1     17689 91392243 7205.6
## - industry:married       1     19620 91394174 7205.6
## - experience:smsa        1     20354 91394908 7205.6
## - smsa:ethnicity         1     23061 91397614 7205.6
## - weeks:education        1     40111 91414665 7205.7
## - occupation:ethnicity   1     43199 91417753 7205.7
## - occupation:married     1     48815 91423369 7205.8
## - industry:gender        1     59503 91434057 7205.8
## - gender:union           1     59823 91434377 7205.8
## - education:ethnicity    1     65265 91439819 7205.9
## - south:smsa             1     76361 91450915 7205.9
## - experience:married     1    100486 91475040 7206.1
## - union:ethnicity        1    104255 91478809 7206.1
## - weeks:ethnicity        1    105962 91480516 7206.1
## - experience:union       1    108205 91482759 7206.1
## - weeks:south            1    115128 91489682 7206.2
## - experience:gender      1    129407 91503961 7206.3
## - weeks:occupation       1    151336 91525890 7206.4
## - industry:education     1    155555 91530109 7206.5
## - married:union          1    179892 91554446 7206.6
## - experience:ethnicity   1    199356 91573910 7206.7
## - industry:ethnicity     1    202324 91576878 7206.8
## - weeks:smsa             1    249640 91624194 7207.1
## - experience:weeks       1    263359 91637913 7207.2
## - married:ethnicity      1    267315 91641869 7207.2
## - smsa:union             1    271766 91646320 7207.2
## <none>                               91374554 7207.4
## - smsa:gender            1    326210 91700764 7207.6
## - industry:smsa          1    424659 91799212 7208.2
## - experience:occupation  1    445963 91820517 7208.3
## - occupation:union       1    473104 91847658 7208.5
## - gender:ethnicity       1    663953 92038506 7209.7
## - occupation:education   1    682836 92057390 7209.9
## - industry:south         1    838793 92213347 7210.9
## - industry:union         1   1036826 92411380 7212.2
## - weeks:gender           1   1095032 92469586 7212.5
## - union:education        1   1411066 92785620 7214.6
## - south:education        1   1714230 93088783 7216.5
## - weeks:married          1   1719115 93093669 7216.5
## 
## Step:  AIC=7205.55
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:smsa        1     17000 91408745 7203.7
## - smsa:ethnicity         1     18606 91410350 7203.7
## - experience:smsa        1     18609 91410353 7203.7
## - industry:married       1     19694 91411438 7203.7
## - occupation:married     1     31806 91423550 7203.8
## - weeks:education        1     40415 91432159 7203.8
## - occupation:ethnicity   1     45014 91436758 7203.8
## - gender:union           1     49392 91441136 7203.9
## - education:ethnicity    1     64206 91455951 7204.0
## - south:smsa             1     75165 91466909 7204.0
## - industry:gender        1     79296 91471040 7204.1
## - experience:married     1     98478 91490222 7204.2
## - union:ethnicity        1    108195 91499939 7204.3
## - weeks:south            1    115300 91507044 7204.3
## - experience:union       1    116056 91507800 7204.3
## - weeks:ethnicity        1    116394 91508138 7204.3
## - experience:gender      1    125855 91517600 7204.4
## - industry:education     1    158734 91550478 7204.6
## - weeks:occupation       1    159956 91551700 7204.6
## - married:union          1    162706 91554450 7204.6
## - industry:ethnicity     1    196886 91588631 7204.8
## - experience:ethnicity   1    197896 91589640 7204.8
## - married:ethnicity      1    259522 91651267 7205.2
## - weeks:smsa             1    262559 91654303 7205.3
## - experience:weeks       1    262864 91654608 7205.3
## - smsa:union             1    269943 91661687 7205.3
## <none>                               91391744 7205.6
## - smsa:gender            1    395113 91786858 7206.1
## - industry:smsa          1    428208 91819952 7206.3
## - experience:occupation  1    440361 91832105 7206.4
## - occupation:union       1    461644 91853388 7206.5
## - occupation:education   1    688566 92080311 7208.0
## - gender:ethnicity       1    712771 92104515 7208.2
## - industry:south         1    831919 92223663 7208.9
## - industry:union         1   1069249 92460994 7210.5
## - weeks:gender           1   1183895 92575639 7211.2
## - union:education        1   1453311 92845055 7212.9
## - south:education        1   1702427 93094171 7214.5
## - weeks:married          1   1841478 93233222 7215.4
## 
## Step:  AIC=7203.66
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:ethnicity         1     17922 91426666 7201.8
## - industry:married       1     21311 91430055 7201.8
## - experience:smsa        1     21327 91430071 7201.8
## - occupation:married     1     26826 91435571 7201.8
## - weeks:education        1     40725 91449469 7201.9
## - occupation:ethnicity   1     47176 91455920 7202.0
## - gender:union           1     48037 91456782 7202.0
## - education:ethnicity    1     65247 91473991 7202.1
## - south:smsa             1     70116 91478861 7202.1
## - industry:gender        1     81317 91490061 7202.2
## - experience:married     1     95534 91504278 7202.3
## - union:ethnicity        1    109629 91518374 7202.4
## - weeks:south            1    114801 91523545 7202.4
## - weeks:ethnicity        1    116168 91524913 7202.4
## - experience:gender      1    126024 91534769 7202.5
## - experience:union       1    129849 91538593 7202.5
## - industry:education     1    147294 91556038 7202.6
## - married:union          1    156034 91564779 7202.7
## - weeks:occupation       1    156638 91565383 7202.7
## - industry:ethnicity     1    197375 91606120 7202.9
## - experience:ethnicity   1    204894 91613638 7203.0
## - weeks:smsa             1    254546 91663291 7203.3
## - smsa:union             1    258736 91667480 7203.3
## - experience:weeks       1    260946 91669690 7203.4
## - married:ethnicity      1    271129 91679874 7203.4
## <none>                               91408745 7203.7
## - smsa:gender            1    391182 91799926 7204.2
## - industry:smsa          1    411218 91819962 7204.3
## - experience:occupation  1    424247 91832991 7204.4
## - occupation:union       1    501696 91910441 7204.9
## - occupation:education   1    671830 92080574 7206.0
## - gender:ethnicity       1    751230 92159975 7206.5
## - industry:south         1    833714 92242458 7207.1
## - industry:union         1   1127234 92535978 7209.0
## - weeks:gender           1   1177229 92585974 7209.3
## - union:education        1   1471572 92880316 7211.2
## - south:education        1   1691432 93100177 7212.6
## - weeks:married          1   1841985 93250730 7213.5
## 
## Step:  AIC=7201.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:married       1     21330 91447997 7199.9
## - experience:smsa        1     23495 91450161 7199.9
## - occupation:married     1     24115 91450782 7199.9
## - weeks:education        1     40137 91466804 7200.0
## - gender:union           1     43186 91469852 7200.1
## - occupation:ethnicity   1     57533 91484199 7200.2
## - south:smsa             1     81667 91508333 7200.3
## - industry:gender        1     82997 91509663 7200.3
## - education:ethnicity    1     90616 91517282 7200.4
## - experience:married     1     93930 91520596 7200.4
## - union:ethnicity        1     96936 91523602 7200.4
## - weeks:ethnicity        1    114677 91541343 7200.5
## - weeks:south            1    115965 91542632 7200.5
## - experience:gender      1    121506 91548173 7200.6
## - experience:union       1    126869 91553535 7200.6
## - married:union          1    151534 91578200 7200.8
## - industry:education     1    157328 91583994 7200.8
## - weeks:occupation       1    162502 91589168 7200.8
## - industry:ethnicity     1    190598 91617264 7201.0
## - experience:ethnicity   1    222831 91649497 7201.2
## - weeks:smsa             1    252389 91679056 7201.4
## - experience:weeks       1    260498 91687164 7201.5
## - smsa:union             1    263873 91690539 7201.5
## - married:ethnicity      1    276656 91703322 7201.6
## <none>                               91426666 7201.8
## - smsa:gender            1    382927 91809593 7202.3
## - industry:smsa          1    416465 91843131 7202.5
## - experience:occupation  1    418286 91844952 7202.5
## - occupation:union       1    493523 91920189 7203.0
## - occupation:education   1    671017 92097683 7204.1
## - gender:ethnicity       1    744522 92171188 7204.6
## - industry:south         1    849931 92276598 7205.3
## - industry:union         1   1113062 92539729 7207.0
## - weeks:gender           1   1201990 92628656 7207.6
## - union:education        1   1468439 92895105 7209.3
## - south:education        1   1705058 93131725 7210.8
## - weeks:married          1   1878944 93305610 7211.9
## 
## Step:  AIC=7199.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:smsa        1     24165 91472162 7198.1
## - occupation:married     1     25409 91473406 7198.1
## - gender:union           1     36054 91484050 7198.2
## - weeks:education        1     46726 91494723 7198.2
## - occupation:ethnicity   1     58581 91506577 7198.3
## - industry:gender        1     62378 91510374 7198.3
## - experience:married     1     83440 91531436 7198.5
## - south:smsa             1     89891 91537888 7198.5
## - education:ethnicity    1     93833 91541830 7198.5
## - weeks:south            1    107662 91555658 7198.6
## - union:ethnicity        1    108123 91556119 7198.6
## - weeks:ethnicity        1    112078 91560074 7198.6
## - experience:gender      1    114597 91562594 7198.7
## - experience:union       1    128856 91576852 7198.8
## - married:union          1    134849 91582846 7198.8
## - industry:education     1    156138 91604135 7198.9
## - weeks:occupation       1    157658 91605654 7198.9
## - industry:ethnicity     1    181886 91629882 7199.1
## - experience:ethnicity   1    228589 91676585 7199.4
## - weeks:smsa             1    246640 91694637 7199.5
## - experience:weeks       1    252860 91700856 7199.6
## - smsa:union             1    255258 91703254 7199.6
## - married:ethnicity      1    267567 91715564 7199.7
## <none>                               91447997 7199.9
## - smsa:gender            1    385844 91833841 7200.4
## - experience:occupation  1    412439 91860436 7200.6
## - industry:smsa          1    438254 91886251 7200.8
## - occupation:union       1    488114 91936111 7201.1
## - occupation:education   1    658867 92106864 7202.2
## - gender:ethnicity       1    735763 92183759 7202.7
## - industry:south         1    855705 92303701 7203.5
## - industry:union         1   1099695 92547692 7205.0
## - weeks:gender           1   1216197 92664194 7205.8
## - union:education        1   1465201 92913197 7207.4
## - south:education        1   1690266 93138262 7208.8
## - weeks:married          1   1911054 93359051 7210.2
## 
## Step:  AIC=7198.08
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:married     1     27214 91499376 7196.3
## - gender:union           1     36173 91508335 7196.3
## - weeks:education        1     47415 91519577 7196.4
## - occupation:ethnicity   1     58633 91530795 7196.5
## - industry:gender        1     60377 91532539 7196.5
## - experience:married     1     89620 91561782 7196.7
## - south:smsa             1     92373 91564535 7196.7
## - education:ethnicity    1     95426 91567588 7196.7
## - union:ethnicity        1    104033 91576195 7196.8
## - experience:gender      1    107012 91579174 7196.8
## - weeks:south            1    107629 91579791 7196.8
## - weeks:ethnicity        1    113805 91585967 7196.8
## - experience:union       1    118126 91590287 7196.8
## - married:union          1    134116 91606278 7196.9
## - industry:education     1    150156 91622317 7197.1
## - weeks:occupation       1    153588 91625750 7197.1
## - industry:ethnicity     1    179847 91652008 7197.2
## - experience:ethnicity   1    218699 91690860 7197.5
## - experience:weeks       1    241028 91713189 7197.6
## - weeks:smsa             1    260665 91732826 7197.8
## - married:ethnicity      1    263929 91736090 7197.8
## - smsa:union             1    266964 91739126 7197.8
## <none>                               91472162 7198.1
## - industry:smsa          1    423052 91895214 7198.8
## - smsa:gender            1    435613 91907775 7198.9
## - experience:occupation  1    462201 91934363 7199.1
## - occupation:union       1    483054 91955215 7199.2
## - occupation:education   1    655183 92127344 7200.3
## - gender:ethnicity       1    728809 92200971 7200.8
## - industry:south         1    866006 92338168 7201.7
## - industry:union         1   1126718 92598879 7203.4
## - weeks:gender           1   1230469 92702630 7204.0
## - union:education        1   1461939 92934101 7205.5
## - south:education        1   1668715 93140876 7206.8
## - weeks:married          1   1915526 93387688 7208.4
## 
## Step:  AIC=7196.25
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:union           1     24521 91523897 7194.4
## - industry:gender        1     42492 91541868 7194.5
## - occupation:ethnicity   1     45483 91544859 7194.5
## - weeks:education        1     46152 91545528 7194.6
## - experience:married     1     81562 91580938 7194.8
## - south:smsa             1     91839 91591215 7194.8
## - education:ethnicity    1     95964 91595340 7194.9
## - experience:gender      1    106367 91605743 7194.9
## - married:union          1    108704 91608080 7195.0
## - weeks:south            1    111022 91610398 7195.0
## - union:ethnicity        1    116632 91616007 7195.0
## - weeks:ethnicity        1    121637 91621013 7195.0
## - experience:union       1    121697 91621073 7195.0
## - industry:education     1    144126 91643502 7195.2
## - weeks:occupation       1    150637 91650013 7195.2
## - industry:ethnicity     1    194053 91693429 7195.5
## - experience:ethnicity   1    219638 91719014 7195.7
## - experience:weeks       1    251198 91750574 7195.9
## - married:ethnicity      1    255197 91754573 7195.9
## - smsa:union             1    261403 91760778 7195.9
## - weeks:smsa             1    262530 91761906 7196.0
## <none>                               91499376 7196.3
## - smsa:gender            1    408406 91907782 7196.9
## - industry:smsa          1    418526 91917902 7197.0
## - experience:occupation  1    436101 91935477 7197.1
## - occupation:union       1    521804 92021180 7197.6
## - occupation:education   1    641790 92141165 7198.4
## - gender:ethnicity       1    702233 92201609 7198.8
## - industry:south         1    878094 92377470 7199.9
## - industry:union         1   1142034 92641410 7201.6
## - weeks:gender           1   1251927 92751303 7202.3
## - union:education        1   1448332 92947708 7203.6
## - south:education        1   1669678 93169054 7205.0
## - weeks:married          1   2039461 93538837 7207.4
## 
## Step:  AIC=7194.41
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:gender        1     36721 91560617 7192.7
## - weeks:education        1     41723 91565619 7192.7
## - occupation:ethnicity   1     42898 91566794 7192.7
## - experience:married     1     83163 91607059 7193.0
## - south:smsa             1     84850 91608747 7193.0
## - married:union          1     88831 91612728 7193.0
## - education:ethnicity    1    100274 91624171 7193.1
## - experience:gender      1    108851 91632748 7193.1
## - union:ethnicity        1    116030 91639926 7193.2
## - weeks:south            1    119829 91643726 7193.2
## - weeks:ethnicity        1    123414 91647311 7193.2
## - experience:union       1    132488 91656385 7193.3
## - industry:education     1    134493 91658390 7193.3
## - weeks:occupation       1    157170 91681067 7193.4
## - industry:ethnicity     1    182444 91706341 7193.6
## - experience:ethnicity   1    233535 91757432 7193.9
## - experience:weeks       1    250494 91774391 7194.0
## - married:ethnicity      1    251663 91775559 7194.0
## - smsa:union             1    263067 91786963 7194.1
## - weeks:smsa             1    268040 91791937 7194.2
## <none>                               91523897 7194.4
## - smsa:gender            1    422425 91946322 7195.2
## - industry:smsa          1    422686 91946583 7195.2
## - experience:occupation  1    428356 91952253 7195.2
## - occupation:union       1    528811 92052707 7195.8
## - occupation:education   1    630567 92154463 7196.5
## - gender:ethnicity       1    697487 92221384 7196.9
## - industry:south         1    887674 92411570 7198.2
## - industry:union         1   1146934 92670831 7199.8
## - weeks:gender           1   1281983 92805880 7200.7
## - union:education        1   1491022 93014919 7202.0
## - south:education        1   1671819 93195716 7203.2
## - weeks:married          1   2026020 93549916 7205.4
## 
## Step:  AIC=7192.65
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:education        1     43059 91603677 7190.9
## - occupation:ethnicity   1     45270 91605887 7190.9
## - education:ethnicity    1     82150 91642767 7191.2
## - experience:married     1     82402 91643020 7191.2
## - south:smsa             1     86945 91647563 7191.2
## - experience:gender      1     91359 91651976 7191.2
## - married:union          1    100244 91660862 7191.3
## - union:ethnicity        1    117665 91678282 7191.4
## - experience:union       1    121657 91682274 7191.4
## - weeks:ethnicity        1    122983 91683600 7191.4
## - industry:education     1    126738 91687355 7191.5
## - weeks:south            1    127391 91688009 7191.5
## - weeks:occupation       1    160971 91721588 7191.7
## - experience:weeks       1    239281 91799899 7192.2
## - married:ethnicity      1    242734 91803351 7192.2
## - experience:ethnicity   1    242879 91803496 7192.2
## - industry:ethnicity     1    253952 91814569 7192.3
## - weeks:smsa             1    268091 91828708 7192.4
## - smsa:union             1    276719 91837336 7192.4
## <none>                               91560617 7192.7
## - industry:smsa          1    406681 91967298 7193.3
## - smsa:gender            1    430952 91991570 7193.4
## - experience:occupation  1    438906 91999523 7193.5
## - occupation:union       1    525486 92086103 7194.1
## - occupation:education   1    639533 92200150 7194.8
## - gender:ethnicity       1    708776 92269393 7195.2
## - industry:south         1    895404 92456021 7196.4
## - industry:union         1   1188027 92748644 7198.3
## - weeks:gender           1   1350715 92911332 7199.4
## - union:education        1   1464888 93025505 7200.1
## - south:education        1   1685709 93246326 7201.5
## - weeks:married          1   2063089 93623706 7203.9
## 
## Step:  AIC=7190.93
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:ethnicity   1     42650 91646326 7189.2
## - experience:married     1     79377 91683054 7189.4
## - experience:gender      1     80236 91683912 7189.5
## - education:ethnicity    1     82696 91686373 7189.5
## - south:smsa             1     94496 91698172 7189.5
## - weeks:ethnicity        1    100938 91704615 7189.6
## - married:union          1    107272 91710949 7189.6
## - union:ethnicity        1    109104 91712780 7189.6
## - industry:education     1    120659 91724336 7189.7
## - experience:union       1    123666 91727343 7189.7
## - weeks:south            1    161510 91765187 7190.0
## - married:ethnicity      1    229487 91833164 7190.4
## - experience:ethnicity   1    240756 91844433 7190.5
## - industry:ethnicity     1    245801 91849478 7190.5
## - weeks:smsa             1    249703 91853379 7190.5
## - experience:weeks       1    267405 91871082 7190.7
## - smsa:union             1    271958 91875635 7190.7
## <none>                               91603677 7190.9
## - industry:smsa          1    409391 92013068 7191.6
## - experience:occupation  1    437316 92040993 7191.8
## - smsa:gender            1    444810 92048486 7191.8
## - occupation:union       1    507879 92111556 7192.2
## - weeks:occupation       1    527801 92131478 7192.3
## - occupation:education   1    616286 92219963 7192.9
## - gender:ethnicity       1    680823 92284500 7193.3
## - industry:south         1    893102 92496779 7194.7
## - industry:union         1   1192834 92796511 7196.6
## - weeks:gender           1   1327694 92931371 7197.5
## - union:education        1   1606155 93209831 7199.3
## - south:education        1   1746342 93350019 7200.2
## - weeks:married          1   2058363 93662040 7202.2
## 
## Step:  AIC=7189.21
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:gender      1     72569 91718895 7187.7
## - experience:married     1     75522 91721848 7187.7
## - weeks:ethnicity        1     99007 91745334 7187.8
## - south:smsa             1    100726 91747053 7187.9
## - married:union          1    109839 91756165 7187.9
## - experience:union       1    111212 91757538 7187.9
## - industry:education     1    119017 91765344 7188.0
## - union:ethnicity        1    158709 91805036 7188.2
## - weeks:south            1    165021 91811347 7188.3
## - education:ethnicity    1    197883 91844209 7188.5
## - weeks:smsa             1    245643 91891969 7188.8
## - industry:ethnicity     1    253128 91899455 7188.8
## - experience:weeks       1    259416 91905742 7188.9
## - smsa:union             1    262957 91909283 7188.9
## - experience:ethnicity   1    263720 91910046 7188.9
## - married:ethnicity      1    277158 91923484 7189.0
## <none>                               91646326 7189.2
## - industry:smsa          1    400475 92046801 7189.8
## - smsa:gender            1    434402 92080728 7190.0
## - experience:occupation  1    462841 92109168 7190.2
## - weeks:occupation       1    546883 92193209 7190.7
## - occupation:union       1    568327 92214654 7190.9
## - occupation:education   1    669547 92315874 7191.5
## - gender:ethnicity       1    907631 92553957 7193.1
## - industry:south         1    915075 92561401 7193.1
## - industry:union         1   1211283 92857609 7195.0
## - weeks:gender           1   1356513 93002839 7195.9
## - union:education        1   1565748 93212074 7197.3
## - south:education        1   1759145 93405471 7198.5
## - weeks:married          1   2074217 93720543 7200.5
## 
## Step:  AIC=7187.68
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:ethnicity + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:married     1     16454 91735349 7185.8
## - weeks:ethnicity        1     92318 91811213 7186.3
## - south:smsa             1     97940 91816835 7186.3
## - experience:union       1     99672 91818567 7186.3
## - married:union          1    109224 91828120 7186.4
## - industry:education     1    115167 91834063 7186.4
## - union:ethnicity        1    151502 91870397 7186.7
## - weeks:south            1    172388 91891283 7186.8
## - education:ethnicity    1    200577 91919472 7187.0
## - experience:weeks       1    240431 91959326 7187.2
## - industry:ethnicity     1    249329 91968224 7187.3
## - weeks:smsa             1    259857 91978752 7187.4
## - smsa:union             1    266700 91985595 7187.4
## <none>                               91718895 7187.7
## - married:ethnicity      1    364918 92083813 7188.0
## - experience:ethnicity   1    381676 92100571 7188.1
## - industry:smsa          1    400833 92119728 7188.3
## - experience:occupation  1    454555 92173450 7188.6
## - smsa:gender            1    492970 92211866 7188.9
## - weeks:occupation       1    546974 92265870 7189.2
## - occupation:union       1    598093 92316988 7189.5
## - occupation:education   1    679627 92398523 7190.1
## - industry:south         1    921381 92640276 7191.6
## - gender:ethnicity       1    959436 92678331 7191.9
## - industry:union         1   1251005 92969901 7193.7
## - weeks:gender           1   1443342 93162237 7195.0
## - union:education        1   1557988 93276884 7195.7
## - south:education        1   1725950 93444846 7196.8
## - weeks:married          1   2076553 93795448 7199.0
## 
## Step:  AIC=7185.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:ethnicity        1     95528 91830877 7184.4
## - south:smsa             1     96442 91831791 7184.4
## - experience:union       1    106702 91842051 7184.5
## - industry:education     1    114288 91849637 7184.5
## - married:union          1    116096 91851445 7184.5
## - union:ethnicity        1    150001 91885350 7184.8
## - weeks:south            1    175557 91910906 7184.9
## - education:ethnicity    1    198063 91933412 7185.1
## - experience:weeks       1    249558 91984907 7185.4
## - industry:ethnicity     1    254155 91989504 7185.4
## - weeks:smsa             1    263816 91999165 7185.5
## - smsa:union             1    266458 92001807 7185.5
## <none>                               91735349 7185.8
## - married:ethnicity      1    363824 92099173 7186.1
## - experience:ethnicity   1    365607 92100956 7186.2
## - industry:smsa          1    398609 92133958 7186.4
## - experience:occupation  1    442613 92177962 7186.6
## - smsa:gender            1    478939 92214288 7186.9
## - weeks:occupation       1    541037 92276386 7187.3
## - occupation:union       1    591791 92327140 7187.6
## - occupation:education   1    671217 92406566 7188.1
## - industry:south         1    914177 92649526 7189.7
## - gender:ethnicity       1   1006255 92741604 7190.3
## - industry:union         1   1249393 92984742 7191.8
## - weeks:gender           1   1432607 93167956 7193.0
## - union:education        1   1569011 93304360 7193.9
## - south:education        1   1765487 93500835 7195.1
## - weeks:married          1   2107284 93842633 7197.3
## 
## Step:  AIC=7184.4
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:smsa             1    103010 91933887 7183.1
## - experience:union       1    115246 91946123 7183.2
## - industry:education     1    116429 91947305 7183.2
## - weeks:south            1    142527 91973404 7183.3
## - married:union          1    147018 91977894 7183.4
## - education:ethnicity    1    156891 91987768 7183.4
## - union:ethnicity        1    161875 91992752 7183.5
## - weeks:smsa             1    213391 92044267 7183.8
## - smsa:union             1    251891 92082768 7184.0
## - experience:weeks       1    285255 92116131 7184.2
## - industry:ethnicity     1    293587 92124463 7184.3
## <none>                               91830877 7184.4
## - industry:smsa          1    402100 92232976 7185.0
## - experience:ethnicity   1    434621 92265498 7185.2
## - experience:occupation  1    444932 92275809 7185.3
## - weeks:occupation       1    480674 92311550 7185.5
## - smsa:gender            1    483644 92314520 7185.5
## - married:ethnicity      1    525658 92356535 7185.8
## - occupation:union       1    585617 92416494 7186.2
## - occupation:education   1    701610 92532486 7186.9
## - industry:south         1    901076 92731952 7188.2
## - gender:ethnicity       1   1165336 92996213 7189.9
## - industry:union         1   1272939 93103816 7190.6
## - weeks:gender           1   1400635 93231511 7191.4
## - union:education        1   1589922 93420799 7192.6
## - south:education        1   1710976 93541853 7193.4
## - weeks:married          1   2028010 93858886 7195.4
## 
## Step:  AIC=7183.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:education     1    106680 92040567 7181.8
## - experience:union       1    111457 92045344 7181.8
## - married:union          1    138956 92072843 7182.0
## - education:ethnicity    1    159058 92092945 7182.1
## - weeks:south            1    164273 92098160 7182.1
## - union:ethnicity        1    177437 92111324 7182.2
## - weeks:smsa             1    209244 92143131 7182.4
## - smsa:union             1    223837 92157724 7182.5
## - experience:weeks       1    276077 92209964 7182.9
## - industry:ethnicity     1    276553 92210440 7182.9
## <none>                               91933887 7183.1
## - industry:smsa          1    367198 92301085 7183.4
## - experience:occupation  1    445661 92379548 7183.9
## - experience:ethnicity   1    458102 92391989 7184.0
## - smsa:gender            1    485151 92419038 7184.2
## - weeks:occupation       1    496360 92430247 7184.3
## - occupation:union       1    534379 92468266 7184.5
## - married:ethnicity      1    560383 92494270 7184.7
## - occupation:education   1    701448 92635335 7185.6
## - industry:south         1    894743 92828630 7186.8
## - gender:ethnicity       1   1165663 93099550 7188.6
## - industry:union         1   1315146 93249033 7189.5
## - weeks:gender           1   1379536 93313423 7189.9
## - union:education        1   1677202 93611089 7191.8
## - weeks:married          1   2008907 93942794 7193.9
## - south:education        1   2072779 94006666 7194.3
## 
## Step:  AIC=7181.76
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:union       1    103702 92144269 7180.4
## - married:union          1    136786 92177353 7180.6
## - education:ethnicity    1    175203 92215770 7180.9
## - weeks:south            1    181940 92222507 7180.9
## - union:ethnicity        1    199964 92240531 7181.1
## - weeks:smsa             1    227771 92268338 7181.2
## - smsa:union             1    239666 92280233 7181.3
## - industry:ethnicity     1    242738 92283305 7181.3
## - experience:weeks       1    269710 92310277 7181.5
## - industry:smsa          1    308384 92348951 7181.8
## <none>                               92040567 7181.8
## - experience:ethnicity   1    467579 92508146 7182.8
## - smsa:gender            1    495308 92535875 7183.0
## - experience:occupation  1    502898 92543465 7183.0
## - married:ethnicity      1    551338 92591905 7183.3
## - weeks:occupation       1    570022 92610589 7183.4
## - occupation:union       1    571383 92611951 7183.4
## - occupation:education   1    604540 92645107 7183.7
## - industry:south         1   1036703 93077270 7186.4
## - gender:ethnicity       1   1193877 93234445 7187.4
## - weeks:gender           1   1434697 93475264 7189.0
## - union:education        1   1666677 93707244 7190.4
## - industry:union         1   1717323 93757891 7190.8
## - south:education        1   2124837 94165404 7193.3
## - weeks:married          1   2160152 94200719 7193.6
## 
## Step:  AIC=7180.43
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:union          1    165016 92309285 7179.5
## - weeks:south            1    170581 92314850 7179.5
## - education:ethnicity    1    170731 92315000 7179.5
## - union:ethnicity        1    203159 92347428 7179.7
## - experience:weeks       1    224369 92368639 7179.9
## - industry:ethnicity     1    229510 92373779 7179.9
## - weeks:smsa             1    250423 92394692 7180.0
## - industry:smsa          1    290321 92434590 7180.3
## <none>                               92144269 7180.4
## - smsa:union             1    321657 92465927 7180.5
## - experience:ethnicity   1    462747 92607016 7181.4
## - smsa:gender            1    475189 92619458 7181.5
## - married:ethnicity      1    534776 92679045 7181.9
## - weeks:occupation       1    579448 92723717 7182.2
## - occupation:union       1    674025 92818294 7182.8
## - occupation:education   1    677830 92822099 7182.8
## - experience:occupation  1    759413 92903682 7183.3
## - industry:south         1   1021806 93166075 7185.0
## - gender:ethnicity       1   1164384 93308653 7185.9
## - weeks:gender           1   1418850 93563119 7187.5
## - union:education        1   1585444 93729713 7188.6
## - industry:union         1   1729388 93873657 7189.5
## - south:education        1   2084083 94228352 7191.7
## - weeks:married          1   2163802 94308071 7192.2
## 
## Step:  AIC=7179.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - education:ethnicity    1    130462 92439747 7178.3
## - weeks:south            1    158071 92467356 7178.5
## - experience:weeks       1    217312 92526597 7178.9
## - industry:ethnicity     1    237370 92546655 7179.0
## - weeks:smsa             1    245747 92555032 7179.1
## - smsa:union             1    288921 92598206 7179.4
## - union:ethnicity        1    295944 92605229 7179.4
## <none>                               92309285 7179.5
## - industry:smsa          1    330146 92639431 7179.6
## - smsa:gender            1    446533 92755818 7180.4
## - experience:ethnicity   1    451973 92761258 7180.4
## - married:ethnicity      1    475100 92784385 7180.6
## - weeks:occupation       1    599334 92908619 7181.3
## - occupation:union       1    652610 92961895 7181.7
## - occupation:education   1    736687 93045972 7182.2
## - experience:occupation  1    794246 93103531 7182.6
## - industry:south         1   1027948 93337233 7184.1
## - gender:ethnicity       1   1140084 93449370 7184.8
## - weeks:gender           1   1343963 93653248 7186.1
## - union:education        1   1571499 93880784 7187.5
## - industry:union         1   1805383 94114668 7189.0
## - south:education        1   2057016 94366301 7190.6
## - weeks:married          1   2200786 94510071 7191.5
## 
## Step:  AIC=7178.34
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:south            1    180354 92620102 7177.5
## - experience:weeks       1    235430 92675177 7177.8
## - weeks:smsa             1    245873 92685620 7177.9
## - smsa:union             1    284711 92724459 7178.2
## - union:ethnicity        1    299872 92739619 7178.3
## - industry:smsa          1    308882 92748629 7178.3
## <none>                               92439747 7178.3
## - industry:ethnicity     1    360928 92800675 7178.7
## - married:ethnicity      1    413502 92853249 7179.0
## - smsa:gender            1    421583 92861331 7179.0
## - experience:ethnicity   1    436254 92876002 7179.1
## - weeks:occupation       1    628800 93068547 7180.4
## - occupation:union       1    641294 93081041 7180.4
## - experience:occupation  1    808729 93248476 7181.5
## - occupation:education   1    848339 93288087 7181.8
## - industry:south         1   1062655 93502402 7183.1
## - gender:ethnicity       1   1137670 93577417 7183.6
## - weeks:gender           1   1392707 93832454 7185.2
## - union:education        1   1541359 93981106 7186.2
## - industry:union         1   1869290 94309037 7188.2
## - south:education        1   2111105 94550853 7189.8
## - weeks:married          1   2333196 94772943 7191.2
## 
## Step:  AIC=7177.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:smsa + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:smsa             1    172792 92792893 7176.6
## - experience:weeks       1    228245 92848346 7177.0
## - industry:smsa          1    311667 92931768 7177.5
## <none>                               92620102 7177.5
## - union:ethnicity        1    314428 92934530 7177.5
## - smsa:union             1    320885 92940986 7177.6
## - industry:ethnicity     1    355606 92975708 7177.8
## - married:ethnicity      1    399021 93019123 7178.1
## - experience:ethnicity   1    435902 93056004 7178.3
## - smsa:gender            1    467222 93087323 7178.5
## - weeks:occupation       1    573987 93194089 7179.2
## - occupation:union       1    698568 93318670 7180.0
## - experience:occupation  1    821734 93441835 7180.8
## - occupation:education   1    845635 93465737 7180.9
## - industry:south         1   1029459 93649561 7182.1
## - gender:ethnicity       1   1176305 93796407 7183.0
## - weeks:gender           1   1377577 93997679 7184.3
## - union:education        1   1621124 94241226 7185.8
## - industry:union         1   1849255 94469357 7187.3
## - south:education        1   2169719 94789821 7189.3
## - weeks:married          1   2372053 94992154 7190.5
## 
## Step:  AIC=7176.6
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:union             1    258082 93050975 7176.3
## - experience:weeks       1    288786 93081679 7176.5
## - union:ethnicity        1    296047 93088940 7176.5
## <none>                               92792893 7176.6
## - industry:smsa          1    318661 93111554 7176.6
## - industry:ethnicity     1    359249 93152143 7176.9
## - married:ethnicity      1    398745 93191638 7177.2
## - smsa:gender            1    424866 93217760 7177.3
## - experience:ethnicity   1    442696 93235589 7177.4
## - weeks:occupation       1    487098 93279991 7177.7
## - occupation:union       1    718100 93510993 7179.2
## - occupation:education   1    871687 93664580 7180.2
## - experience:occupation  1    879035 93671929 7180.2
## - industry:south         1   1063711 93856604 7181.4
## - gender:ethnicity       1   1179928 93972821 7182.1
## - weeks:gender           1   1269071 94061964 7182.7
## - union:education        1   1530461 94323354 7184.3
## - industry:union         1   1781020 94573914 7185.9
## - south:education        1   2084738 94877631 7187.8
## - weeks:married          1   2332192 95125086 7189.4
## 
## Step:  AIC=7176.26
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - union:ethnicity        1    233127 93284103 7175.7
## <none>                               93050975 7176.3
## - experience:weeks       1    347031 93398006 7176.5
## - industry:ethnicity     1    360592 93411567 7176.6
## - smsa:gender            1    374647 93425622 7176.6
## - married:ethnicity      1    413932 93464907 7176.9
## - industry:smsa          1    434838 93485813 7177.0
## - experience:ethnicity   1    436180 93487155 7177.0
## - weeks:occupation       1    482233 93533209 7177.3
## - occupation:union       1    790925 93841900 7179.3
## - experience:occupation  1    861950 93912926 7179.7
## - occupation:education   1    888278 93939253 7179.9
## - industry:south         1   1137537 94188512 7181.5
## - gender:ethnicity       1   1203368 94254343 7181.9
## - weeks:gender           1   1292681 94343656 7182.5
## - union:education        1   1642035 94693010 7184.7
## - industry:union         1   1781824 94832799 7185.5
## - south:education        1   2149198 95200173 7187.8
## - weeks:married          1   2330415 95381390 7189.0
## 
## Step:  AIC=7175.75
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education
## 
##                         Df Sum of Sq      RSS    AIC
## <none>                               93284103 7175.7
## - experience:ethnicity   1    342374 93626477 7175.9
## - experience:weeks       1    357898 93642000 7176.0
## - married:ethnicity      1    382852 93666955 7176.2
## - smsa:gender            1    389928 93674031 7176.2
## - industry:smsa          1    431444 93715546 7176.5
## - weeks:occupation       1    454255 93738358 7176.6
## - industry:ethnicity     1    584573 93868675 7177.5
## - occupation:union       1    770225 94054327 7178.6
## - experience:occupation  1    793944 94078046 7178.8
## - occupation:education   1    794605 94078708 7178.8
## - gender:ethnicity       1   1021861 94305963 7180.2
## - industry:south         1   1150084 94434187 7181.0
## - weeks:gender           1   1244968 94529070 7181.6
## - union:education        1   1764736 95048838 7184.9
## - industry:union         1   1883835 95167938 7185.6
## - south:education        1   2103290 95387392 7187.0
## - weeks:married          1   2214309 95498411 7187.7
## 
## Call:
## lm(formula = YM ~ experience + weeks + occupation + industry + 
##     south + smsa + married + gender + union + education + ethnicity + 
##     experience:weeks + experience:occupation + experience:ethnicity + 
##     weeks:occupation + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + married:ethnicity + 
##     gender:ethnicity + union:education, data = mydata2)
## 
## Coefficients:
##            (Intercept)              experience                   weeks  
##              -973.6307                 26.3765                 10.2584  
##            occupation1               industry1                  south1  
##             -1017.3840                251.1260                662.0379  
##                  smsa1                married1                 gender1  
##                35.8154              -1887.1285               1936.9768  
##                 union1               education              ethnicity1  
##               991.7270                 78.5235                165.6754  
##       experience:weeks  experience:occupation1   experience:ethnicity1  
##                -0.5124                  7.2153                 -9.0179  
##      weeks:occupation1          weeks:married1           weeks:gender1  
##                12.7170                 41.4631                -37.1696  
##     occupation1:union1   occupation1:education        industry1:south1  
##              -215.2853                 37.5504               -226.2304  
##        industry1:smsa1        industry1:union1    industry1:ethnicity1  
##              -122.2004               -262.7235                274.1885  
##       south1:education           smsa1:gender1     married1:ethnicity1  
##               -50.7068                207.6874                327.3527  
##     gender1:ethnicity1        union1:education  
##              -570.5685                -60.4342
#########################################################################
##### Model selection: stepwise algorithms
##### Example 6: first-order models and models with interactions, Forward stepwise
#########################################################################

model0 = lm(YM~1, data=mydata2)
modelF = lm(YM~.^2, data=mydata2)

step(model0, scope=list(lower=model0, upper=modelF), direction="both")
## Start:  AIC=7468.15
## YM ~ 1
## 
##              Df Sum of Sq       RSS    AIC
## + education   1  32538301 134997861 7341.7
## + occupation  1  22992077 144544085 7382.3
## + gender      1  12829545 154706617 7422.7
## + married     1  10932833 156603329 7430.0
## + smsa        1   8127541 159408621 7440.6
## + ethnicity   1   5344585 162191577 7450.9
## + south       1   4329602 163206560 7454.6
## + experience  1   1362281 166173881 7465.3
## + union       1    995691 166540471 7466.6
## <none>                    167536162 7468.1
## + weeks       1    321828 167214334 7469.0
## + industry    1    121663 167414499 7469.7
## 
## Step:  AIC=7341.66
## YM ~ education
## 
##              Df Sum of Sq       RSS    AIC
## + gender      1  12779707 122218154 7284.5
## + married     1  10254719 124743143 7296.7
## + experience  1   6226451 128771410 7315.6
## + smsa        1   3415108 131582754 7328.4
## + industry    1   3308035 131689826 7328.9
## + ethnicity   1   2694785 132303077 7331.7
## + occupation  1   2192036 132805826 7333.9
## + south       1   2135767 132862094 7334.2
## <none>                    134997861 7341.7
## + union       1    330373 134667489 7342.2
## + weeks       1    320629 134677232 7342.2
## - education   1  32538301 167536162 7468.1
## 
## Step:  AIC=7284.49
## YM ~ education + gender
## 
##                    Df Sum of Sq       RSS    AIC
## + smsa              1   5133833 117084321 7261.0
## + experience        1   4667646 117550508 7263.3
## + occupation        1   3076803 119141352 7271.3
## + south             1   1530433 120687721 7279.0
## + industry          1   1421780 120796374 7279.5
## + married           1    885628 121332526 7282.2
## + ethnicity         1    830636 121387519 7282.4
## <none>                          122218154 7284.5
## + weeks             1     64671 122153483 7286.2
## + gender:education  1     41500 122176655 7286.3
## + union             1     10215 122207940 7286.4
## - gender            1  12779707 134997861 7341.7
## - education         1  32488463 154706617 7422.7
## 
## Step:  AIC=7260.96
## YM ~ education + gender + smsa
## 
##                    Df Sum of Sq       RSS    AIC
## + experience        1   3681824 113402497 7243.9
## + occupation        1   2438824 114645498 7250.4
## + ethnicity         1   1494428 115589893 7255.3
## + industry          1   1289920 115794402 7256.4
## + married           1   1059185 116025137 7257.5
## + south             1    881624 116202697 7258.5
## + smsa:education    1    494481 116589841 7260.4
## <none>                          117084321 7261.0
## + smsa:gender       1     90405 116993916 7262.5
## + weeks             1     32761 117051560 7262.8
## + gender:education  1     28736 117055586 7262.8
## + union             1      5150 117079172 7262.9
## - smsa              1   5133833 122218154 7284.5
## - gender            1  14498432 131582754 7328.4
## - education         1  26944998 144029319 7382.2
## 
## Step:  AIC=7243.95
## YM ~ education + gender + smsa + experience
## 
##                        Df Sum of Sq       RSS    AIC
## + occupation            1   2112437 111290061 7234.8
## + ethnicity             1   1599078 111803420 7237.5
## + industry              1    897795 112504702 7241.2
## + south                 1    666655 112735843 7242.4
## + smsa:education        1    598877 112803621 7242.8
## + married               1    580521 112821976 7242.9
## <none>                              113402497 7243.9
## + experience:gender     1    335405 113067093 7244.2
## + smsa:gender           1    177714 113224783 7245.0
## + weeks                 1    175973 113226525 7245.0
## + gender:education      1     53580 113348918 7245.7
## + experience:education  1     18554 113383944 7245.8
## + union                 1      2300 113400198 7245.9
## + experience:smsa       1       948 113401550 7245.9
## - experience            1   3681824 117084321 7261.0
## - smsa                  1   4148011 117550508 7263.3
## - gender                1  12786981 126189478 7305.5
## - education             1  30244311 143646808 7382.6
## 
## Step:  AIC=7234.76
## YM ~ education + gender + smsa + experience + occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + ethnicity              1   1490793 109799268 7228.7
## + occupation:education   1   1385398 109904663 7229.3
## + industry               1   1277208 110012853 7229.9
## + south                  1    898041 110392020 7231.9
## + married                1    592449 110697611 7233.6
## + smsa:education         1    424265 110865796 7234.5
## <none>                               111290061 7234.8
## + experience:occupation  1    346486 110943575 7234.9
## + experience:gender      1    197085 111092976 7235.7
## + smsa:gender            1    175541 111114520 7235.8
## + weeks                  1    150302 111139759 7236.0
## + union                  1    149432 111140629 7236.0
## + occupation:gender      1     78695 111211366 7236.3
## + experience:education   1     77734 111212327 7236.3
## + gender:education       1     60964 111229097 7236.4
## + occupation:smsa        1     29381 111260680 7236.6
## + experience:smsa        1      9924 111280137 7236.7
## - occupation             1   2112437 113402497 7243.9
## - experience             1   3355437 114645498 7250.4
## - smsa                   1   3658161 114948222 7252.0
## - education              1  11406668 122696729 7290.8
## - gender                 1  13469904 124759965 7300.7
## 
## Step:  AIC=7228.73
## YM ~ education + gender + smsa + experience + occupation + ethnicity
## 
##                         Df Sum of Sq       RSS    AIC
## + occupation:education   1   1353525 108445743 7223.4
## + industry               1   1141696 108657572 7224.5
## + occupation:ethnicity   1   1066339 108732929 7224.9
## + south                  1    646695 109152573 7227.2
## + education:ethnicity    1    493449 109305819 7228.1
## + married                1    413169 109386099 7228.5
## + experience:occupation  1    383390 109415878 7228.7
## <none>                               109799268 7228.7
## + occupation:gender      1    362778 109436490 7228.8
## + smsa:education         1    362161 109437106 7228.8
## + gender:ethnicity       1    253895 109545373 7229.4
## + gender:education       1    218448 109580820 7229.5
## + union                  1    157390 109641878 7229.9
## + experience:education   1    137568 109661700 7230.0
## + weeks                  1    111460 109687807 7230.1
## + experience:ethnicity   1     75548 109723720 7230.3
## + smsa:ethnicity         1     74879 109724389 7230.3
## + smsa:gender            1     70979 109728288 7230.3
## + experience:gender      1     51982 109747285 7230.5
## + experience:smsa        1     20688 109778580 7230.6
## + occupation:smsa        1     13851 109785417 7230.7
## - ethnicity              1   1490793 111290061 7234.8
## - occupation             1   2004152 111803420 7237.5
## - experience             1   3459487 113258754 7245.2
## - smsa                   1   4229138 114028405 7249.2
## - education              1  10612905 120412173 7281.6
## - gender                 1  11246775 121046043 7284.8
## 
## Step:  AIC=7223.35
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     education:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + industry               1   1067950 107377793 7219.5
## + occupation:ethnicity   1    832174 107613568 7220.8
## + experience:occupation  1    789177 107656565 7221.0
## + south                  1    721189 107724554 7221.4
## + married                1    496447 107949296 7222.6
## + experience:education   1    383380 108062363 7223.2
## <none>                               108445743 7223.4
## + education:ethnicity    1    311668 108134075 7223.6
## + occupation:gender      1    306264 108139479 7223.7
## + gender:ethnicity       1    281068 108164675 7223.8
## + gender:education       1    263202 108182541 7223.9
## + union                  1    213582 108232161 7224.2
## + weeks                  1    199242 108246501 7224.3
## + smsa:education         1    114026 108331716 7224.7
## + experience:ethnicity   1     88428 108357314 7224.9
## + smsa:gender            1     42042 108403701 7225.1
## + smsa:ethnicity         1     37358 108408385 7225.1
## + experience:smsa        1     36806 108408937 7225.2
## + experience:gender      1     36382 108409361 7225.2
## + occupation:smsa        1       331 108445412 7225.4
## - education:occupation   1   1353525 109799268 7228.7
## - ethnicity              1   1458920 109904663 7229.3
## - experience             1   3059586 111505329 7237.9
## - smsa                   1   4365186 112810929 7244.8
## - gender                 1  10987853 119433596 7278.8
## 
## Step:  AIC=7219.47
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + industry:education     1   1124480 106253313 7215.2
## + occupation:industry    1    909910 106467882 7216.4
## + occupation:ethnicity   1    810821 106566971 7217.0
## + experience:occupation  1    684802 106692991 7217.7
## + south                  1    557481 106820312 7218.4
## + married                1    445524 106932269 7219.0
## <none>                               107377793 7219.5
## + gender:education       1    307168 107070625 7219.8
## + education:ethnicity    1    303694 107074099 7219.8
## + experience:education   1    302250 107075543 7219.8
## + industry:smsa          1    280595 107097198 7219.9
## + gender:ethnicity       1    263658 107114135 7220.0
## + occupation:gender      1    258262 107119531 7220.0
## + weeks                  1    215449 107162344 7220.3
## + union                  1    163053 107214740 7220.6
## + industry:ethnicity     1     90010 107287783 7221.0
## + experience:ethnicity   1     80121 107297671 7221.0
## + smsa:education         1     73622 107304170 7221.1
## + smsa:ethnicity         1     48461 107329331 7221.2
## + smsa:gender            1     48333 107329460 7221.2
## + experience:gender      1     46302 107331491 7221.2
## + industry:gender        1     39298 107338495 7221.2
## + experience:industry    1     22060 107355733 7221.3
## + experience:smsa        1     11669 107366124 7221.4
## + occupation:smsa        1       864 107376929 7221.5
## - industry               1   1067950 108445743 7223.4
## - education:occupation   1   1279779 108657572 7224.5
## - ethnicity              1   1329925 108707718 7224.8
## - experience             1   2655061 110032854 7232.0
## - smsa                   1   4227663 111605456 7240.4
## - gender                 1   9744817 117122610 7269.2
## 
## Step:  AIC=7215.2
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry
## 
##                         Df Sum of Sq       RSS    AIC
## + occupation:ethnicity   1    676151 105577162 7213.4
## + industry:smsa          1    560151 105693162 7214.1
## + experience:occupation  1    535565 105717748 7214.2
## + married                1    510970 105742344 7214.3
## + south                  1    485529 105767784 7214.5
## <none>                               106253313 7215.2
## + union                  1    335354 105917959 7215.3
## + education:ethnicity    1    200010 106053304 7216.1
## + industry:ethnicity     1    198607 106054706 7216.1
## + gender:ethnicity       1    189630 106063683 7216.1
## + experience:education   1    184881 106068433 7216.2
## + occupation:gender      1    154977 106098336 7216.3
## + occupation:industry    1    146477 106106836 7216.4
## + weeks                  1    142935 106110378 7216.4
## + gender:education       1    120361 106132952 7216.5
## + industry:gender        1     57349 106195964 7216.9
## + smsa:education         1     53934 106199379 7216.9
## + experience:ethnicity   1     52127 106201186 7216.9
## + experience:gender      1     44874 106208439 7216.9
## + smsa:gender            1     33897 106219417 7217.0
## + smsa:ethnicity         1     14163 106239150 7217.1
## + experience:smsa        1     13161 106240153 7217.1
## + occupation:smsa        1      1613 106251700 7217.2
## + experience:industry    1      1005 106252308 7217.2
## - education:industry     1   1124480 107377793 7219.5
## - ethnicity              1   1399028 107652342 7221.0
## - education:occupation   1   1965534 108218847 7224.1
## - experience             1   2412783 108666096 7226.6
## - smsa                   1   3997700 110251013 7235.2
## - gender                 1   9983524 116236837 7266.6
## 
## Step:  AIC=7213.4
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity
## 
##                         Df Sum of Sq       RSS    AIC
## + industry:smsa          1    644500 104932662 7211.8
## + experience:occupation  1    552534 105024628 7212.3
## + south                  1    464656 105112506 7212.8
## + married                1    440262 105136900 7212.9
## + union                  1    371162 105206000 7213.3
## <none>                               105577162 7213.4
## + experience:education   1    221586 105355576 7214.2
## + weeks                  1    138933 105438229 7214.6
## + occupation:industry    1    118387 105458775 7214.7
## + gender:education       1     94754 105482408 7214.9
## + experience:gender      1     86202 105490960 7214.9
## + smsa:education         1     79477 105497685 7215.0
## + experience:ethnicity   1     76083 105501079 7215.0
## + industry:ethnicity     1     74014 105503148 7215.0
## + smsa:gender            1     71543 105505619 7215.0
## + occupation:gender      1     61415 105515747 7215.1
## + gender:ethnicity       1     45833 105531329 7215.1
## + industry:gender        1     36856 105540306 7215.2
## - occupation:ethnicity   1    676151 106253313 7215.2
## + experience:smsa        1     16310 105560853 7215.3
## + occupation:smsa        1      6967 105570195 7215.4
## + education:ethnicity    1       989 105576173 7215.4
## + smsa:ethnicity         1       483 105576679 7215.4
## + experience:industry    1       385 105576777 7215.4
## - education:industry     1    989809 106566971 7217.0
## - education:occupation   1   1657483 107234645 7220.7
## - experience             1   2391313 107968475 7224.7
## - smsa                   1   3993196 109570358 7233.5
## - gender                 1  10578920 116156082 7268.2
## 
## Step:  AIC=7211.76
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity + 
##     smsa:industry
## 
##                         Df Sum of Sq       RSS    AIC
## + experience:occupation  1    530344 104402318 7210.7
## + south                  1    484279 104448383 7211.0
## + married                1    450919 104481743 7211.2
## <none>                               104932662 7211.8
## + union                  1    327870 104604792 7211.9
## + experience:education   1    181278 104751384 7212.7
## + smsa:gender            1    172324 104760338 7212.8
## + industry:ethnicity     1    156178 104776484 7212.9
## + occupation:industry    1    153909 104778754 7212.9
## + weeks                  1    119779 104812883 7213.1
## + experience:gender      1    112328 104820334 7213.1
## + experience:ethnicity   1     91884 104840779 7213.2
## + gender:education       1     86676 104845986 7213.3
## + occupation:gender      1     72525 104860137 7213.3
## + industry:gender        1     66698 104865964 7213.4
## - smsa:industry          1    644500 105577162 7213.4
## + experience:smsa        1     49222 104883440 7213.5
## + gender:ethnicity       1     25558 104907104 7213.6
## + occupation:smsa        1     12806 104919857 7213.7
## + experience:industry    1      8722 104923940 7213.7
## + education:ethnicity    1      5070 104927592 7213.7
## + smsa:education         1      3164 104929499 7213.7
## + smsa:ethnicity         1        47 104932615 7213.8
## - occupation:ethnicity   1    760500 105693162 7214.1
## - education:industry     1   1272866 106205528 7216.9
## - education:occupation   1   1728451 106661113 7219.5
## - experience             1   2625216 107557878 7224.5
## - gender                 1  10761341 115694004 7267.8
## 
## Step:  AIC=7210.74
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + education:occupation + education:industry + occupation:ethnicity + 
##     smsa:industry + experience:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + south                  1    471832 103930487 7210.0
## + married                1    453018 103949300 7210.2
## <none>                               104402318 7210.7
## + union                  1    303878 104098440 7211.0
## + industry:ethnicity     1    197575 104204743 7211.6
## - experience:occupation  1    530344 104932662 7211.8
## + smsa:gender            1    161451 104240867 7211.8
## + weeks                  1    108363 104293955 7212.1
## + occupation:industry    1    105173 104297145 7212.1
## + experience:gender      1    101740 104300578 7212.2
## - smsa:industry          1    622309 105024628 7212.3
## + industry:gender        1     73553 104328765 7212.3
## + gender:education       1     64519 104337800 7212.4
## + experience:ethnicity   1     61764 104340554 7212.4
## + experience:industry    1     52310 104350008 7212.4
## + occupation:gender      1     43082 104359236 7212.5
## + gender:ethnicity       1     32020 104370298 7212.6
## + occupation:smsa        1     28581 104373737 7212.6
## + experience:smsa        1     14214 104388105 7212.7
## + education:ethnicity    1      6402 104395916 7212.7
## + experience:education   1       898 104401421 7212.7
## + smsa:ethnicity         1       100 104402218 7212.7
## + smsa:education         1        24 104402294 7212.7
## - occupation:ethnicity   1    776544 105178862 7213.2
## - education:industry     1   1109154 105511472 7215.0
## - education:occupation   1   2022769 106425087 7220.2
## - gender                 1  10509063 114911382 7265.8
## 
## Step:  AIC=7210.05
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation
## 
##                         Df Sum of Sq       RSS    AIC
## + south:education        1    519525 103410961 7209.1
## + married                1    447670 103482816 7209.5
## <none>                               103930487 7210.0
## + industry:south         1    229392 103701095 7210.7
## - south                  1    471832 104402318 7210.7
## + industry:ethnicity     1    198305 103732181 7210.9
## + union                  1    192120 103738367 7210.9
## - experience:occupation  1    517896 104448383 7211.0
## + south:smsa             1    161737 103768749 7211.1
## + smsa:gender            1    154361 103776126 7211.2
## + experience:south       1    124131 103806355 7211.3
## + experience:gender      1    107397 103823089 7211.4
## + occupation:industry    1     99264 103831222 7211.5
## + weeks                  1     98545 103831941 7211.5
## + industry:gender        1     73494 103856993 7211.6
## - smsa:industry          1    641596 104572083 7211.7
## + experience:ethnicity   1     57734 103872753 7211.7
## + gender:education       1     49484 103881003 7211.8
## + gender:ethnicity       1     40744 103889743 7211.8
## + occupation:gender      1     33842 103896645 7211.9
## + south:gender           1     33772 103896715 7211.9
## + south:ethnicity        1     30036 103900451 7211.9
## + experience:industry    1     27283 103903204 7211.9
## + occupation:south       1     24829 103905658 7211.9
## + smsa:education         1     13291 103917196 7212.0
## + occupation:smsa        1     11076 103919410 7212.0
## + education:ethnicity    1      8894 103921593 7212.0
## + experience:smsa        1      6650 103923837 7212.0
## + smsa:ethnicity         1      3178 103927308 7212.0
## + experience:education   1       582 103929905 7212.0
## - occupation:ethnicity   1    755205 104685691 7212.4
## - education:industry     1   1049232 104979719 7214.0
## - education:occupation   1   2070776 106001263 7219.8
## - gender                 1  10372262 114302748 7264.7
## 
## Step:  AIC=7209.07
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south
## 
##                         Df Sum of Sq       RSS    AIC
## + industry:south         1    551781 102859180 7207.9
## + married                1    417873 102993088 7208.7
## <none>                               103410961 7209.1
## - experience:occupation  1    471903 103882864 7209.8
## + union                  1    223565 103187397 7209.8
## + industry:ethnicity     1    186588 103224374 7210.0
## - education:south        1    519525 103930487 7210.0
## + smsa:gender            1    164018 103246944 7210.1
## + experience:gender      1    157590 103253371 7210.2
## - smsa:industry          1    545499 103956460 7210.2
## + weeks                  1    138772 103272190 7210.3
## + occupation:south       1    124031 103286930 7210.4
## + south:ethnicity        1     64933 103346029 7210.7
## + occupation:industry    1     63574 103347387 7210.7
## + industry:gender        1     46721 103364240 7210.8
## + experience:ethnicity   1     45195 103365766 7210.8
## + south:smsa             1     45100 103365862 7210.8
## + experience:industry    1     42364 103368598 7210.8
## + south:gender           1     40530 103370431 7210.8
## + gender:ethnicity       1     40192 103370769 7210.8
## + gender:education       1     40048 103370913 7210.8
## + experience:south       1     34167 103376794 7210.9
## + occupation:gender      1     33210 103377751 7210.9
## - occupation:ethnicity   1    665249 104076211 7210.9
## + occupation:smsa        1     25832 103385130 7210.9
## + experience:smsa        1     17478 103393483 7211.0
## + experience:education   1      5433 103405528 7211.0
## + smsa:education         1      4209 103406752 7211.0
## + education:ethnicity    1      3080 103407881 7211.1
## + smsa:ethnicity         1        41 103410920 7211.1
## - education:industry     1    990371 104401332 7212.7
## - education:occupation   1   1775656 105186618 7217.2
## - gender                 1  10152459 113563420 7262.8
## 
## Step:  AIC=7207.88
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south + industry:south
## 
##                         Df Sum of Sq       RSS    AIC
## + married                1    421610 102437569 7207.4
## <none>                               102859180 7207.9
## + industry:ethnicity     1    288163 102571017 7208.2
## + union                  1    204920 102654260 7208.7
## + smsa:gender            1    170512 102688668 7208.9
## + experience:gender      1    149982 102709198 7209.0
## - industry:south         1    551781 103410961 7209.1
## + weeks                  1    126871 102732309 7209.2
## - experience:occupation  1    584101 103443280 7209.3
## + south:ethnicity        1     96035 102763145 7209.3
## + occupation:industry    1     72664 102786516 7209.5
## + industry:gender        1     56754 102802426 7209.6
## + south:smsa             1     56696 102802484 7209.6
## + occupation:south       1     56655 102802525 7209.6
## + gender:education       1     55718 102803462 7209.6
## - occupation:ethnicity   1    638168 103497348 7209.6
## + experience:ethnicity   1     47454 102811726 7209.6
## + occupation:gender      1     43619 102815561 7209.6
## + occupation:smsa        1     33120 102826060 7209.7
## + experience:south       1     28202 102830978 7209.7
## + gender:ethnicity       1     26742 102832438 7209.7
## + experience:industry    1     23980 102835200 7209.7
## - smsa:industry          1    669860 103529040 7209.7
## + experience:smsa        1     13352 102845828 7209.8
## + experience:education   1      7933 102851246 7209.8
## + education:ethnicity    1      5026 102854154 7209.9
## + south:gender           1      5016 102854163 7209.9
## + smsa:education         1      2611 102856568 7209.9
## + smsa:ethnicity         1      1097 102858083 7209.9
## - education:industry     1    744167 103603347 7210.2
## - education:south        1    841915 103701095 7210.7
## - education:occupation   1   1761213 104620393 7216.0
## - gender                 1  10200657 113059837 7262.1
## 
## Step:  AIC=7207.44
## YM ~ education + gender + smsa + experience + occupation + ethnicity + 
##     industry + south + married + education:occupation + education:industry + 
##     occupation:ethnicity + smsa:industry + experience:occupation + 
##     education:south + industry:south
## 
##                         Df Sum of Sq       RSS    AIC
## <none>                               102437569 7207.4
## - married                1    421610 102859180 7207.9
## + industry:ethnicity     1    260702 102176867 7207.9
## + smsa:gender            1    179014 102258555 7208.4
## + union                  1    176884 102260686 7208.4
## + experience:gender      1    141401 102296169 7208.6
## - industry:south         1    555519 102993088 7208.7
## - occupation:ethnicity   1    574375 103011945 7208.8
## + weeks                  1    109027 102328542 7208.8
## - experience:occupation  1    588099 103025668 7208.8
## + smsa:married           1     96432 102341138 7208.9
## + occupation:industry    1     86460 102351110 7208.9
## + experience:ethnicity   1     78662 102358907 7209.0
## + industry:married       1     76039 102361530 7209.0
## + south:ethnicity        1     68629 102368941 7209.0
## + industry:gender        1     66334 102371236 7209.1
## + occupation:south       1     60065 102377504 7209.1
## + south:smsa             1     59869 102377701 7209.1
## + gender:education       1     51981 102385589 7209.1
## + occupation:gender      1     43170 102394399 7209.2
## + occupation:smsa        1     39144 102398425 7209.2
## + experience:industry    1     34537 102403032 7209.2
## + married:ethnicity      1     31341 102406228 7209.3
## + experience:south       1     30287 102407283 7209.3
## + married:education      1     25224 102412345 7209.3
## + occupation:married     1     19975 102417594 7209.3
## + gender:ethnicity       1     19351 102418218 7209.3
## + education:ethnicity    1     13010 102424559 7209.4
## + experience:married     1     12854 102424716 7209.4
## - smsa:industry          1    683347 103120916 7209.4
## + experience:smsa        1      7030 102430539 7209.4
## + south:married          1      6446 102431124 7209.4
## + smsa:education         1      4111 102433459 7209.4
## + experience:education   1      3936 102433633 7209.4
## + south:gender           1      1698 102435871 7209.4
## + married:gender         1         1 102437568 7209.4
## + smsa:ethnicity         1         0 102437569 7209.4
## - education:industry     1    798788 103236357 7210.1
## - education:south        1    806953 103244523 7210.1
## - education:occupation   1   1882412 104319981 7216.3
## - gender                 1   3594555 106032125 7226.0
## 
## Call:
## lm(formula = YM ~ education + gender + smsa + experience + occupation + 
##     ethnicity + industry + south + married + education:occupation + 
##     education:industry + occupation:ethnicity + smsa:industry + 
##     experience:occupation + education:south + industry:south, 
##     data = mydata2)
## 
## Coefficients:
##            (Intercept)               education                 gender1  
##                  4.433                  28.979                 358.467  
##                  smsa1              experience             occupation1  
##                249.499                   2.762                -692.981  
##             ethnicity1               industry1                  south1  
##                -87.488                -171.323                 372.508  
##               married1   education:occupation1     education:industry1  
##                 97.683                  57.684                  30.091  
## occupation1:ethnicity1         smsa1:industry1  experience:occupation1  
##               -258.882                -150.198                   6.140  
##       education:south1        industry1:south1  
##                -30.238                -155.169
step(modelF, scope=list(lower=model0, upper=modelF), direction="both")
## Start:  AIC=7239
## YM ~ (experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity)^2
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:education   1         2 91306975 7237.0
## - married:education      1        86 91307059 7237.0
## - occupation:industry    1       618 91307591 7237.0
## - south:ethnicity        1       935 91307908 7237.0
## - south:union            1      1058 91308031 7237.0
## - experience:industry    1      1253 91308226 7237.0
## - gender:education       1      1302 91308275 7237.0
## - smsa:education         1      1486 91308459 7237.0
## - experience:south       1      2308 91309281 7237.0
## - weeks:union            1      3410 91310383 7237.0
## - occupation:south       1      3613 91310586 7237.0
## - smsa:married           1      7733 91314706 7237.1
## - weeks:industry         1      8024 91314997 7237.1
## - occupation:smsa        1      8372 91315345 7237.1
## - occupation:gender      1      9729 91316702 7237.1
## - south:married          1     10650 91317623 7237.1
## - experience:smsa        1     12485 91319458 7237.1
## - married:gender         1     18994 91325967 7237.1
## - smsa:ethnicity         1     20640 91327613 7237.1
## - south:gender           1     21308 91328281 7237.1
## - industry:married       1     24114 91331087 7237.2
## - weeks:education        1     24415 91331388 7237.2
## - occupation:married     1     27245 91334218 7237.2
## - education:ethnicity    1     44180 91351154 7237.3
## - occupation:ethnicity   1     44502 91351475 7237.3
## - industry:gender        1     63323 91370296 7237.4
## - weeks:ethnicity        1     64682 91371655 7237.4
## - south:smsa             1     64812 91371785 7237.4
## - union:ethnicity        1     76462 91383435 7237.5
## - gender:union           1     79645 91386618 7237.5
## - experience:married     1     87133 91394106 7237.6
## - industry:education     1     95204 91402177 7237.6
## - experience:union       1    100023 91406996 7237.7
## - weeks:occupation       1    102123 91409096 7237.7
## - weeks:south            1    106528 91413501 7237.7
## - experience:gender      1    126347 91433320 7237.8
## - smsa:gender            1    144747 91451720 7237.9
## - experience:ethnicity   1    150793 91457767 7238.0
## - weeks:smsa             1    156782 91463756 7238.0
## - married:union          1    190094 91497067 7238.2
## - industry:ethnicity     1    202542 91509515 7238.3
## - married:ethnicity      1    207185 91514158 7238.3
## - experience:weeks       1    241038 91548011 7238.6
## - smsa:union             1    247436 91554409 7238.6
## - experience:occupation  1    279817 91586790 7238.8
## <none>                               91306973 7239.0
## - industry:smsa          1    395448 91702421 7239.6
## - occupation:union       1    411142 91718115 7239.7
## - gender:ethnicity       1    562906 91869879 7240.7
## - occupation:education   1    620025 91926998 7241.0
## - industry:south         1    752501 92059474 7241.9
## - weeks:gender           1    838327 92145300 7242.4
## - industry:union         1    900259 92207232 7242.8
## - south:education        1   1168423 92475396 7244.6
## - union:education        1   1301618 92608591 7245.4
## - weeks:married          1   1505379 92812352 7246.7
## 
## Step:  AIC=7237
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:education + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:education      1        84 91307059 7235.0
## - occupation:industry    1       620 91307596 7235.0
## - south:ethnicity        1       933 91307908 7235.0
## - south:union            1      1057 91308032 7235.0
## - experience:industry    1      1257 91308232 7235.0
## - gender:education       1      1303 91308279 7235.0
## - smsa:education         1      1484 91308459 7235.0
## - experience:south       1      2390 91309365 7235.0
## - weeks:union            1      3421 91310396 7235.0
## - occupation:south       1      3633 91310609 7235.0
## - smsa:married           1      7732 91314707 7235.1
## - weeks:industry         1      8022 91314997 7235.1
## - occupation:smsa        1      8374 91315349 7235.1
## - occupation:gender      1      9727 91316703 7235.1
## - south:married          1     10653 91317628 7235.1
## - experience:smsa        1     12807 91319783 7235.1
## - married:gender         1     19081 91326057 7235.1
## - smsa:ethnicity         1     20653 91327629 7235.1
## - south:gender           1     21384 91328360 7235.1
## - industry:married       1     24263 91331238 7235.2
## - weeks:education        1     24543 91331519 7235.2
## - occupation:married     1     27348 91334324 7235.2
## - education:ethnicity    1     44392 91351368 7235.3
## - occupation:ethnicity   1     44500 91351475 7235.3
## - industry:gender        1     63586 91370561 7235.4
## - south:smsa             1     64843 91371818 7235.4
## - weeks:ethnicity        1     64860 91371835 7235.4
## - union:ethnicity        1     76486 91383462 7235.5
## - gender:union           1     79660 91386636 7235.5
## - experience:married     1     87333 91394308 7235.6
## - industry:education     1     95350 91402326 7235.6
## - experience:union       1    101742 91408718 7235.7
## - weeks:occupation       1    102533 91409509 7235.7
## - weeks:south            1    107228 91414204 7235.7
## - experience:gender      1    127006 91433981 7235.8
## - smsa:gender            1    144756 91451731 7235.9
## - experience:ethnicity   1    150947 91457923 7236.0
## - weeks:smsa             1    156782 91463758 7236.0
## - married:union          1    190407 91497382 7236.2
## - industry:ethnicity     1    202927 91509903 7236.3
## - married:ethnicity      1    207392 91514367 7236.3
## - experience:weeks       1    241189 91548164 7236.6
## - smsa:union             1    247669 91554645 7236.6
## <none>                               91306975 7237.0
## - industry:smsa          1    397490 91704466 7237.6
## - experience:occupation  1    410984 91717960 7237.7
## - occupation:union       1    422118 91729093 7237.7
## - gender:ethnicity       1    563265 91870240 7238.7
## + experience:education   1         2 91306973 7239.0
## - occupation:education   1    621310 91928286 7239.0
## - industry:south         1    754162 92061138 7239.9
## - weeks:gender           1    843006 92149982 7240.5
## - industry:union         1    904630 92211605 7240.9
## - south:education        1   1180347 92487322 7242.6
## - union:education        1   1318095 92625071 7243.5
## - weeks:married          1   1507936 92814912 7244.7
## 
## Step:  AIC=7235
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:industry + occupation:south + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:union + south:education + south:ethnicity + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:industry    1       655 91307714 7233.0
## - south:ethnicity        1       938 91307997 7233.0
## - south:union            1      1043 91308102 7233.0
## - experience:industry    1      1318 91308377 7233.0
## - smsa:education         1      1460 91308519 7233.0
## - gender:education       1      2086 91309145 7233.0
## - experience:south       1      2376 91309435 7233.0
## - weeks:union            1      3408 91310467 7233.0
## - occupation:south       1      3698 91310757 7233.0
## - smsa:married           1      7696 91314755 7233.1
## - weeks:industry         1      8185 91315244 7233.1
## - occupation:smsa        1      8455 91315514 7233.1
## - south:married          1     10656 91317715 7233.1
## - experience:smsa        1     12992 91320051 7233.1
## - occupation:gender      1     15753 91322812 7233.1
## - married:gender         1     18998 91326057 7233.1
## - smsa:ethnicity         1     20570 91327629 7233.1
## - south:gender           1     21398 91328457 7233.1
## - weeks:education        1     24626 91331685 7233.2
## - industry:married       1     26885 91333944 7233.2
## - education:ethnicity    1     44479 91351538 7233.3
## - occupation:ethnicity   1     44751 91351810 7233.3
## - occupation:married     1     60906 91367965 7233.4
## - south:smsa             1     64928 91371987 7233.4
## - industry:gender        1     66135 91373194 7233.4
## - weeks:ethnicity        1     66321 91373380 7233.4
## - union:ethnicity        1     76698 91383757 7233.5
## - gender:union           1     79751 91386810 7233.5
## - experience:married     1     89098 91396157 7233.6
## - industry:education     1     95307 91402366 7233.6
## - experience:union       1    101844 91408903 7233.7
## - weeks:occupation       1    102452 91409511 7233.7
## - weeks:south            1    107633 91414692 7233.7
## - experience:gender      1    127691 91434750 7233.8
## - smsa:gender            1    144694 91451753 7233.9
## - experience:ethnicity   1    151353 91458412 7234.0
## - weeks:smsa             1    156729 91463788 7234.0
## - married:union          1    190406 91497465 7234.2
## - industry:ethnicity     1    202860 91509919 7234.3
## - married:ethnicity      1    236420 91543479 7234.5
## - experience:weeks       1    242203 91549262 7234.6
## - smsa:union             1    247678 91554737 7234.6
## <none>                               91307059 7235.0
## - industry:smsa          1    397407 91704467 7235.6
## - experience:occupation  1    410932 91717991 7235.7
## - occupation:union       1    422222 91729281 7235.7
## + married:education      1        84 91306975 7237.0
## + experience:education   1         0 91307059 7237.0
## - gender:ethnicity       1    621670 91928729 7237.0
## - occupation:education   1    621762 91928821 7237.0
## - industry:south         1    755862 92062921 7237.9
## - weeks:gender           1    843241 92150300 7238.5
## - industry:union         1    904547 92211606 7238.9
## - south:education        1   1180683 92487742 7240.6
## - union:education        1   1319487 92626546 7241.5
## - weeks:married          1   1514222 92821281 7242.8
## 
## Step:  AIC=7233
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + south:ethnicity + smsa:married + smsa:gender + 
##     smsa:union + smsa:education + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:education + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:ethnicity        1       894 91308609 7231.0
## - south:union            1      1100 91308815 7231.0
## - experience:industry    1      1131 91308845 7231.0
## - smsa:education         1      1302 91309017 7231.0
## - gender:education       1      1747 91309461 7231.0
## - experience:south       1      2243 91309958 7231.0
## - weeks:union            1      3477 91311191 7231.0
## - occupation:south       1      3543 91311257 7231.0
## - smsa:married           1      7559 91315274 7231.1
## - weeks:industry         1      8188 91315903 7231.1
## - occupation:smsa        1      8340 91316054 7231.1
## - south:married          1     10496 91318211 7231.1
## - experience:smsa        1     13368 91321082 7231.1
## - occupation:gender      1     16780 91324494 7231.1
## - married:gender         1     19004 91326719 7231.1
## - smsa:ethnicity         1     20751 91328465 7231.1
## - south:gender           1     21158 91328872 7231.1
## - weeks:education        1     25791 91333505 7231.2
## - industry:married       1     26940 91334654 7231.2
## - occupation:ethnicity   1     44209 91351924 7231.3
## - education:ethnicity    1     45216 91352931 7231.3
## - occupation:married     1     60251 91367966 7231.4
## - south:smsa             1     64518 91372232 7231.4
## - industry:gender        1     65577 91373291 7231.4
## - weeks:ethnicity        1     67968 91375683 7231.4
## - union:ethnicity        1     77438 91385153 7231.5
## - gender:union           1     79225 91386939 7231.5
## - experience:married     1     89676 91397391 7231.6
## - weeks:occupation       1    101939 91409653 7231.7
## - experience:union       1    102977 91410692 7231.7
## - weeks:south            1    108557 91416272 7231.7
## - experience:gender      1    128598 91436312 7231.8
## - industry:education     1    143217 91450931 7231.9
## - smsa:gender            1    144843 91452557 7231.9
## - experience:ethnicity   1    152497 91460211 7232.0
## - weeks:smsa             1    156504 91464219 7232.0
## - married:union          1    189990 91497704 7232.2
## - industry:ethnicity     1    203710 91511424 7232.3
## - married:ethnicity      1    237397 91545111 7232.5
## - experience:weeks       1    243623 91551337 7232.6
## - smsa:union             1    248743 91556458 7232.6
## <none>                               91307714 7233.0
## - industry:smsa          1    397791 91705505 7233.6
## - experience:occupation  1    412653 91720368 7233.7
## - occupation:union       1    426855 91734570 7233.8
## + occupation:industry    1       655 91307059 7235.0
## + married:education      1       119 91307596 7235.0
## + experience:education   1         1 91307714 7235.0
## - occupation:education   1    621645 91929359 7235.0
## - gender:ethnicity       1    626490 91934205 7235.1
## - industry:south         1    758603 92066317 7235.9
## - weeks:gender           1    842590 92150305 7236.5
## - industry:union         1   1034938 92342652 7237.7
## - south:education        1   1181633 92489348 7238.7
## - union:education        1   1332643 92640357 7239.6
## - weeks:married          1   1513613 92821327 7240.8
## 
## Step:  AIC=7231.01
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:union + 
##     south:education + smsa:married + smsa:gender + smsa:union + 
##     smsa:education + smsa:ethnicity + married:gender + married:union + 
##     married:ethnicity + gender:union + gender:education + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:union            1      1105 91309714 7229.0
## - experience:industry    1      1117 91309726 7229.0
## - smsa:education         1      1252 91309861 7229.0
## - gender:education       1      1727 91310335 7229.0
## - experience:south       1      2552 91311161 7229.0
## - weeks:union            1      3354 91311963 7229.0
## - occupation:south       1      3740 91312349 7229.0
## - smsa:married           1      7467 91316076 7229.1
## - weeks:industry         1      7787 91316396 7229.1
## - occupation:smsa        1      8195 91316804 7229.1
## - south:married          1     10035 91318644 7229.1
## - experience:smsa        1     13158 91321767 7229.1
## - occupation:gender      1     16014 91324622 7229.1
## - married:gender         1     19165 91327774 7229.1
## - south:gender           1     22202 91330811 7229.2
## - smsa:ethnicity         1     22937 91331546 7229.2
## - industry:married       1     26432 91335041 7229.2
## - weeks:education        1     27066 91335675 7229.2
## - occupation:ethnicity   1     45927 91354535 7229.3
## - education:ethnicity    1     46242 91354851 7229.3
## - occupation:married     1     59706 91368315 7229.4
## - industry:gender        1     66906 91375515 7229.4
## - weeks:ethnicity        1     69598 91378207 7229.5
## - south:smsa             1     72426 91381035 7229.5
## - gender:union           1     78677 91387286 7229.5
## - union:ethnicity        1     89603 91398212 7229.6
## - experience:married     1     90060 91398668 7229.6
## - weeks:occupation       1    101177 91409786 7229.7
## - experience:union       1    102250 91410859 7229.7
## - weeks:south            1    107679 91416288 7229.7
## - experience:gender      1    128151 91436760 7229.8
## - industry:education     1    144749 91453358 7230.0
## - smsa:gender            1    146220 91454828 7230.0
## - weeks:smsa             1    156815 91465423 7230.0
## - experience:ethnicity   1    162705 91471314 7230.1
## - married:union          1    192822 91501431 7230.3
## - industry:ethnicity     1    204624 91513233 7230.3
## - experience:weeks       1    243385 91551994 7230.6
## - smsa:union             1    248153 91556762 7230.6
## - married:ethnicity      1    255771 91564380 7230.7
## <none>                               91308609 7231.0
## - industry:smsa          1    400501 91709110 7231.6
## - experience:occupation  1    411762 91720371 7231.7
## - occupation:union       1    437048 91745657 7231.9
## + south:ethnicity        1       894 91307714 7233.0
## + occupation:industry    1       612 91307997 7233.0
## + married:education      1       124 91308485 7233.0
## + experience:education   1         0 91308609 7233.0
## - occupation:education   1    623737 91932346 7233.1
## - gender:ethnicity       1    634497 91943106 7233.1
## - industry:south         1    758484 92067092 7233.9
## - weeks:gender           1    896795 92205403 7234.8
## - industry:union         1   1034530 92343138 7235.7
## - south:education        1   1182880 92491489 7236.7
## - union:education        1   1332718 92641327 7237.6
## - weeks:married          1   1570636 92879244 7239.2
## 
## Step:  AIC=7229.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:industry + experience:south + 
##     experience:smsa + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:industry + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:union + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:industry    1      1087 91310801 7227.0
## - smsa:education         1      1422 91311135 7227.0
## - gender:education       1      1727 91311440 7227.0
## - experience:south       1      2304 91312018 7227.0
## - weeks:union            1      3183 91312897 7227.0
## - occupation:south       1      5314 91315028 7227.1
## - occupation:smsa        1      7325 91317038 7227.1
## - weeks:industry         1      7561 91317274 7227.1
## - smsa:married           1      7616 91317330 7227.1
## - south:married          1     10679 91320393 7227.1
## - experience:smsa        1     13141 91322854 7227.1
## - occupation:gender      1     15627 91325340 7227.1
## - married:gender         1     18935 91328649 7227.1
## - south:gender           1     21354 91331067 7227.2
## - smsa:ethnicity         1     22401 91332115 7227.2
## - industry:married       1     25952 91335665 7227.2
## - weeks:education        1     27745 91337458 7227.2
## - education:ethnicity    1     47106 91356819 7227.3
## - occupation:ethnicity   1     48537 91358251 7227.3
## - occupation:married     1     59072 91368786 7227.4
## - industry:gender        1     66784 91376498 7227.5
## - weeks:ethnicity        1     70281 91379994 7227.5
## - south:smsa             1     74168 91383881 7227.5
## - gender:union           1     77574 91387288 7227.5
## - union:ethnicity        1     88632 91398345 7227.6
## - experience:married     1     92173 91401886 7227.6
## - weeks:occupation       1    100385 91410098 7227.7
## - experience:union       1    101329 91411043 7227.7
## - weeks:south            1    107123 91416836 7227.7
## - experience:gender      1    128486 91438199 7227.9
## - industry:education     1    143665 91453378 7228.0
## - smsa:gender            1    146103 91455816 7228.0
## - weeks:smsa             1    158735 91468448 7228.1
## - experience:ethnicity   1    162464 91472178 7228.1
## - married:union          1    192607 91502321 7228.3
## - industry:ethnicity     1    204550 91514263 7228.3
## - experience:weeks       1    243451 91553164 7228.6
## - smsa:union             1    252834 91562548 7228.7
## - married:ethnicity      1    258376 91568089 7228.7
## <none>                               91309714 7229.0
## - industry:smsa          1    407013 91716727 7229.7
## - experience:occupation  1    422158 91731872 7229.8
## - occupation:union       1    447226 91756939 7229.9
## + south:union            1      1105 91308609 7231.0
## + south:ethnicity        1       899 91308815 7231.0
## + occupation:industry    1       667 91309046 7231.0
## + married:education      1       107 91309606 7231.0
## + experience:education   1         1 91309713 7231.0
## - occupation:education   1    630284 91939997 7231.1
## - gender:ethnicity       1    634198 91943911 7231.1
## - industry:south         1    766957 92076671 7232.0
## - weeks:gender           1    898271 92207985 7232.8
## - industry:union         1   1033427 92343140 7233.7
## - south:education        1   1190365 92500078 7234.7
## - union:education        1   1380414 92690128 7235.9
## - weeks:married          1   1570625 92880339 7237.2
## 
## Step:  AIC=7227.02
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:education + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:education + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:education         1      1342 91312143 7225.0
## - gender:education       1      1666 91312467 7225.0
## - experience:south       1      1838 91312638 7225.0
## - weeks:union            1      3087 91313888 7225.0
## - occupation:south       1      5086 91315886 7225.1
## - weeks:industry         1      7030 91317830 7225.1
## - smsa:married           1      7557 91318358 7225.1
## - occupation:smsa        1      7717 91318518 7225.1
## - south:married          1     11108 91321909 7225.1
## - experience:smsa        1     13292 91324093 7225.1
## - occupation:gender      1     15599 91326400 7225.1
## - married:gender         1     19115 91329915 7225.1
## - south:gender           1     21809 91332609 7225.2
## - smsa:ethnicity         1     22234 91333034 7225.2
## - industry:married       1     25124 91335925 7225.2
## - weeks:education        1     27583 91338384 7225.2
## - education:ethnicity    1     47495 91358296 7225.3
## - occupation:ethnicity   1     48161 91358961 7225.3
## - occupation:married     1     60106 91370907 7225.4
## - industry:gender        1     66629 91377429 7225.5
## - weeks:ethnicity        1     69830 91380631 7225.5
## - south:smsa             1     74029 91384830 7225.5
## - gender:union           1     78783 91389583 7225.5
## - union:ethnicity        1     87983 91398784 7225.6
## - experience:married     1     92371 91403171 7225.6
## - weeks:occupation       1    101606 91412407 7225.7
## - experience:union       1    102933 91413734 7225.7
## - weeks:south            1    106514 91417314 7225.7
## - experience:gender      1    127800 91438600 7225.9
## - smsa:gender            1    146555 91457356 7226.0
## - industry:education     1    158263 91469064 7226.1
## - weeks:smsa             1    159069 91469869 7226.1
## - experience:ethnicity   1    161453 91472253 7226.1
## - married:union          1    194039 91504839 7226.3
## - industry:ethnicity     1    204282 91515082 7226.4
## - experience:weeks       1    242367 91553167 7226.6
## - smsa:union             1    251810 91562611 7226.7
## - married:ethnicity      1    260542 91571342 7226.7
## <none>                               91310801 7227.0
## - industry:smsa          1    421468 91732269 7227.8
## - experience:occupation  1    436887 91747688 7227.9
## - occupation:union       1    446139 91756939 7227.9
## + experience:industry    1      1087 91309714 7229.0
## + south:union            1      1075 91309726 7229.0
## + south:ethnicity        1       886 91309915 7229.0
## + occupation:industry    1       481 91310319 7229.0
## + married:education      1       162 91310638 7229.0
## + experience:education   1         0 91310801 7229.0
## - occupation:education   1    629812 91940613 7229.1
## - gender:ethnicity       1    636293 91947094 7229.2
## - industry:south         1    768557 92079357 7230.0
## - weeks:gender           1    898368 92209169 7230.9
## - industry:union         1   1037784 92348585 7231.7
## - south:education        1   1189279 92500079 7232.7
## - union:education        1   1385837 92696637 7234.0
## - weeks:married          1   1572634 92883435 7235.2
## 
## Step:  AIC=7225.03
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:south + experience:smsa + 
##     experience:married + experience:gender + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:industry + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:union + weeks:education + weeks:ethnicity + occupation:south + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:south       1      1717 91313860 7223.0
## - gender:education       1      1905 91314048 7223.0
## - weeks:union            1      3051 91315194 7223.1
## - occupation:south       1      4334 91316477 7223.1
## - weeks:industry         1      7045 91319187 7223.1
## - smsa:married           1      7313 91319455 7223.1
## - south:married          1     11262 91323404 7223.1
## - occupation:gender      1     15426 91327569 7223.1
## - experience:smsa        1     16694 91328837 7223.1
## - occupation:smsa        1     17469 91329612 7223.1
## - married:gender         1     18927 91331070 7223.2
## - smsa:ethnicity         1     21150 91333292 7223.2
## - south:gender           1     21720 91333863 7223.2
## - industry:married       1     24906 91337049 7223.2
## - weeks:education        1     27314 91339457 7223.2
## - occupation:ethnicity   1     47067 91359210 7223.3
## - education:ethnicity    1     53868 91366011 7223.4
## - occupation:married     1     60788 91372931 7223.4
## - industry:gender        1     66322 91378465 7223.5
## - weeks:ethnicity        1     69706 91381849 7223.5
## - south:smsa             1     72725 91384868 7223.5
## - gender:union           1     77765 91389908 7223.5
## - union:ethnicity        1     87305 91399448 7223.6
## - experience:married     1     91564 91403707 7223.6
## - weeks:occupation       1    101710 91413853 7223.7
## - experience:union       1    103284 91415427 7223.7
## - weeks:south            1    105397 91417540 7223.7
## - experience:gender      1    127824 91439967 7223.9
## - smsa:gender            1    145532 91457675 7224.0
## - industry:education     1    157406 91469549 7224.1
## - weeks:smsa             1    157727 91469870 7224.1
## - experience:ethnicity   1    163042 91475185 7224.1
## - married:union          1    193490 91505633 7224.3
## - industry:ethnicity     1    204054 91516197 7224.4
## - experience:weeks       1    242817 91554960 7224.6
## - smsa:union             1    250961 91563104 7224.7
## - married:ethnicity      1    262066 91574209 7224.7
## <none>                               91312143 7225.0
## - industry:smsa          1    423467 91735609 7225.8
## - experience:occupation  1    435581 91747724 7225.9
## - occupation:union       1    444852 91756995 7225.9
## + smsa:education         1      1342 91310801 7227.0
## + south:union            1      1238 91310905 7227.0
## + experience:industry    1      1008 91311135 7227.0
## + south:ethnicity        1       835 91311308 7227.0
## + occupation:industry    1       357 91311786 7227.0
## + married:education      1       121 91312022 7227.0
## + experience:education   1         1 91312142 7227.0
## - gender:ethnicity       1    636551 91948694 7227.2
## - occupation:education   1    652919 91965062 7227.3
## - industry:south         1    776195 92088338 7228.1
## - weeks:gender           1    897093 92209236 7228.9
## - industry:union         1   1036806 92348949 7229.8
## - south:education        1   1239977 92552120 7231.1
## - union:education        1   1397651 92709794 7232.1
## - weeks:married          1   1571293 92883435 7233.2
## 
## Step:  AIC=7223.04
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:education + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:education       1      1745 91315605 7221.1
## - weeks:union            1      2552 91316412 7221.1
## - occupation:south       1      4081 91317941 7221.1
## - weeks:industry         1      7273 91321133 7221.1
## - smsa:married           1      7344 91321204 7221.1
## - south:married          1     12279 91326139 7221.1
## - occupation:gender      1     15768 91329628 7221.1
## - occupation:smsa        1     17485 91331344 7221.2
## - married:gender         1     17811 91331670 7221.2
## - experience:smsa        1     19356 91333216 7221.2
## - south:gender           1     21269 91335128 7221.2
## - smsa:ethnicity         1     21986 91335846 7221.2
## - industry:married       1     24403 91338263 7221.2
## - weeks:education        1     28395 91342254 7221.2
## - occupation:ethnicity   1     46884 91360744 7221.4
## - education:ethnicity    1     55145 91369005 7221.4
## - occupation:married     1     62542 91376402 7221.5
## - industry:gender        1     65614 91379473 7221.5
## - weeks:ethnicity        1     69275 91383135 7221.5
## - south:smsa             1     74376 91388236 7221.5
## - gender:union           1     78727 91392587 7221.6
## - experience:married     1     90246 91404106 7221.6
## - union:ethnicity        1     91101 91404961 7221.6
## - weeks:occupation       1    101362 91415222 7221.7
## - experience:union       1    102218 91416078 7221.7
## - weeks:south            1    104300 91418160 7221.7
## - experience:gender      1    126269 91440129 7221.9
## - smsa:gender            1    145837 91459697 7222.0
## - industry:education     1    156397 91470257 7222.1
## - weeks:smsa             1    157214 91471074 7222.1
## - experience:ethnicity   1    179239 91493099 7222.2
## - married:union          1    199058 91512918 7222.3
## - industry:ethnicity     1    204337 91518197 7222.4
## - experience:weeks       1    241536 91555396 7222.6
## - smsa:union             1    252694 91566554 7222.7
## - married:ethnicity      1    261860 91575719 7222.7
## <none>                               91313860 7223.0
## - industry:smsa          1    423650 91737509 7223.8
## - experience:occupation  1    440113 91753972 7223.9
## - occupation:union       1    445680 91759540 7223.9
## + experience:south       1      1717 91312143 7225.0
## + smsa:education         1      1222 91312638 7225.0
## + south:ethnicity        1      1085 91312775 7225.0
## + south:union            1      1004 91312856 7225.0
## + experience:industry    1       577 91313283 7225.0
## + occupation:industry    1       296 91313564 7225.0
## + married:education      1        96 91313764 7225.0
## + experience:education   1        30 91313830 7225.0
## - gender:ethnicity       1    638664 91952524 7225.2
## - occupation:education   1    655286 91969146 7225.3
## - industry:south         1    775025 92088885 7226.1
## - weeks:gender           1    895377 92209236 7226.9
## - industry:union         1   1035201 92349061 7227.8
## - south:education        1   1304488 92618348 7229.5
## - union:education        1   1403408 92717268 7230.1
## - weeks:married          1   1571747 92885606 7231.2
## 
## Step:  AIC=7221.06
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:union + weeks:education + 
##     weeks:ethnicity + occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:union            1      2668 91318272 7219.1
## - occupation:south       1      4367 91319972 7219.1
## - weeks:industry         1      6825 91322429 7219.1
## - smsa:married           1      7490 91323095 7219.1
## - south:married          1     12573 91328178 7219.1
## - married:gender         1     16938 91332542 7219.2
## - occupation:smsa        1     16950 91332555 7219.2
## - experience:smsa        1     19484 91335088 7219.2
## - smsa:ethnicity         1     21367 91336972 7219.2
## - south:gender           1     21664 91337269 7219.2
## - occupation:gender      1     24385 91339990 7219.2
## - industry:married       1     24408 91340012 7219.2
## - weeks:education        1     30894 91346498 7219.3
## - occupation:ethnicity   1     45308 91360913 7219.4
## - education:ethnicity    1     59815 91375420 7219.4
## - occupation:married     1     62958 91378563 7219.5
## - industry:gender        1     64608 91380213 7219.5
## - weeks:ethnicity        1     69280 91384884 7219.5
## - south:smsa             1     74123 91389728 7219.5
## - gender:union           1     81714 91397318 7219.6
## - experience:married     1     90675 91406280 7219.6
## - union:ethnicity        1     91061 91406666 7219.6
## - weeks:occupation       1    100261 91415865 7219.7
## - experience:union       1    103019 91418623 7219.7
## - weeks:south            1    104522 91420126 7219.7
## - experience:gender      1    125629 91441233 7219.9
## - smsa:gender            1    148130 91463734 7220.0
## - weeks:smsa             1    156892 91472496 7220.1
## - industry:education     1    166052 91481657 7220.1
## - experience:ethnicity   1    181902 91497507 7220.2
## - married:union          1    199765 91515370 7220.4
## - industry:ethnicity     1    202699 91518303 7220.4
## - experience:weeks       1    247836 91563441 7220.7
## - smsa:union             1    250959 91566563 7220.7
## - married:ethnicity      1    272586 91588190 7220.8
## <none>                               91315605 7221.1
## - industry:smsa          1    425397 91741002 7221.8
## - experience:occupation  1    440749 91756353 7221.9
## - occupation:union       1    451247 91766851 7222.0
## + gender:education       1      1745 91313860 7223.0
## + experience:south       1      1557 91314048 7223.0
## + smsa:education         1      1445 91314159 7223.0
## + south:ethnicity        1      1045 91314559 7223.0
## + south:union            1      1028 91314576 7223.0
## + married:education      1       699 91314906 7223.1
## + experience:industry    1       543 91315061 7223.1
## + experience:education   1       141 91315463 7223.1
## + occupation:industry    1        91 91315514 7223.1
## - occupation:education   1    654644 91970249 7223.3
## - gender:ethnicity       1    668144 91983749 7223.4
## - industry:south         1    773281 92088886 7224.1
## - weeks:gender           1    897886 92213491 7224.9
## - industry:union         1   1034299 92349904 7225.8
## - south:education        1   1307257 92622861 7227.5
## - union:education        1   1402900 92718505 7228.1
## - weeks:married          1   1571155 92886760 7229.2
## 
## Step:  AIC=7219.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:south + occupation:smsa + occupation:married + 
##     occupation:gender + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:south       1      3893 91322166 7217.1
## - weeks:industry         1      6916 91325189 7217.1
## - smsa:married           1      7675 91325947 7217.1
## - south:married          1     12776 91331048 7217.2
## - married:gender         1     17144 91335417 7217.2
## - experience:smsa        1     17755 91336028 7217.2
## - occupation:smsa        1     18227 91336499 7217.2
## - smsa:ethnicity         1     21099 91339371 7217.2
## - south:gender           1     21461 91339733 7217.2
## - occupation:gender      1     24316 91342588 7217.2
## - industry:married       1     25173 91343445 7217.2
## - weeks:education        1     32162 91350434 7217.3
## - occupation:ethnicity   1     45552 91363825 7217.4
## - education:ethnicity    1     59925 91378197 7217.5
## - industry:gender        1     64148 91382421 7217.5
## - occupation:married     1     64380 91382652 7217.5
## - weeks:ethnicity        1     74558 91392830 7217.6
## - south:smsa             1     75658 91393930 7217.6
## - gender:union           1     79966 91398238 7217.6
## - experience:married     1     90317 91408589 7217.7
## - union:ethnicity        1     90694 91408967 7217.7
## - experience:union       1    100497 91418770 7217.7
## - weeks:south            1    101897 91420169 7217.7
## - weeks:occupation       1    116904 91435176 7217.8
## - experience:gender      1    124392 91442664 7217.9
## - smsa:gender            1    148530 91466802 7218.0
## - industry:education     1    165536 91483808 7218.2
## - experience:ethnicity   1    181221 91499493 7218.3
## - weeks:smsa             1    200247 91518520 7218.4
## - industry:ethnicity     1    200951 91519223 7218.4
## - married:union          1    203103 91521376 7218.4
## - experience:weeks       1    245208 91563481 7218.7
## - smsa:union             1    271016 91589289 7218.8
## - married:ethnicity      1    273184 91591456 7218.9
## <none>                               91318272 7219.1
## - industry:smsa          1    422790 91741062 7219.8
## - experience:occupation  1    443420 91761692 7220.0
## - occupation:union       1    448761 91767034 7220.0
## + weeks:union            1      2668 91315605 7221.1
## + gender:education       1      1860 91316412 7221.1
## + smsa:education         1      1437 91316835 7221.1
## + experience:south       1      1071 91317201 7221.1
## + south:union            1       908 91317364 7221.1
## + south:ethnicity        1       886 91317387 7221.1
## + married:education      1       770 91317502 7221.1
## + experience:industry    1       532 91317741 7221.1
## + experience:education   1       172 91318100 7221.1
## + occupation:industry    1       117 91318155 7221.1
## - occupation:education   1    660097 91978370 7221.4
## - gender:ethnicity       1    667219 91985491 7221.4
## - industry:south         1    772424 92090696 7222.1
## - weeks:gender           1    900033 92218305 7222.9
## - industry:union         1   1033007 92351279 7223.8
## - south:education        1   1307956 92626228 7225.5
## - union:education        1   1408689 92726961 7226.2
## - weeks:married          1   1586335 92904608 7227.3
## 
## Step:  AIC=7217.1
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:married + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:married           1      7707 91329872 7215.1
## - weeks:industry         1      7809 91329974 7215.1
## - south:married          1     12580 91334746 7215.2
## - married:gender         1     17096 91339261 7215.2
## - experience:smsa        1     17273 91339439 7215.2
## - occupation:smsa        1     20465 91342631 7215.2
## - south:gender           1     20777 91342942 7215.2
## - smsa:ethnicity         1     22236 91344402 7215.2
## - occupation:gender      1     24075 91346241 7215.3
## - industry:married       1     24991 91347157 7215.3
## - weeks:education        1     33460 91355626 7215.3
## - occupation:ethnicity   1     42773 91364938 7215.4
## - education:ethnicity    1     60640 91382806 7215.5
## - occupation:married     1     63679 91385845 7215.5
## - industry:gender        1     63934 91386100 7215.5
## - south:smsa             1     72845 91395011 7215.6
## - weeks:ethnicity        1     77439 91399605 7215.6
## - gender:union           1     79870 91402036 7215.6
## - experience:married     1     89189 91411354 7215.7
## - union:ethnicity        1     95765 91417931 7215.7
## - experience:union       1    101071 91423237 7215.8
## - weeks:south            1    101856 91424022 7215.8
## - weeks:occupation       1    114285 91436450 7215.8
## - experience:gender      1    123614 91445779 7215.9
## - smsa:gender            1    149012 91471178 7216.1
## - industry:education     1    162028 91484194 7216.2
## - experience:ethnicity   1    180620 91502786 7216.3
## - weeks:smsa             1    200350 91522515 7216.4
## - married:union          1    202554 91524720 7216.4
## - industry:ethnicity     1    204837 91527003 7216.4
## - experience:weeks       1    243664 91565830 7216.7
## - married:ethnicity      1    269662 91591827 7216.9
## - smsa:union             1    282666 91604831 7216.9
## <none>                               91322166 7217.1
## - industry:smsa          1    424610 91746776 7217.9
## - experience:occupation  1    442474 91764640 7218.0
## - occupation:union       1    473189 91795355 7218.2
## + occupation:south       1      3893 91318272 7219.1
## + weeks:union            1      2194 91319972 7219.1
## + gender:education       1      2128 91320038 7219.1
## + south:union            1      2110 91320055 7219.1
## + south:ethnicity        1      1111 91321054 7219.1
## + experience:south       1       906 91321259 7219.1
## + married:education      1       794 91321372 7219.1
## + smsa:education         1       705 91321461 7219.1
## + experience:industry    1       429 91321736 7219.1
## + experience:education   1       250 91321916 7219.1
## + occupation:industry    1        73 91322093 7219.1
## - occupation:education   1    657721 91979886 7219.4
## - gender:ethnicity       1    664937 91987103 7219.4
## - industry:south         1    810849 92133015 7220.4
## - weeks:gender           1    898963 92221129 7220.9
## - industry:union         1   1041789 92363954 7221.8
## - union:education        1   1413780 92735945 7224.2
## - weeks:married          1   1586977 92909143 7225.3
## - south:education        1   1743189 93065355 7226.3
## 
## Step:  AIC=7215.15
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:industry + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:education + weeks:ethnicity + 
##     occupation:smsa + occupation:married + occupation:gender + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:married + south:gender + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:industry         1      6887 91336760 7213.2
## - south:married          1     16580 91346452 7213.3
## - occupation:smsa        1     19084 91348957 7213.3
## - married:gender         1     19348 91349220 7213.3
## - experience:smsa        1     19445 91349317 7213.3
## - occupation:gender      1     20812 91350684 7213.3
## - industry:married       1     21738 91351611 7213.3
## - smsa:ethnicity         1     23180 91353052 7213.3
## - south:gender           1     24786 91354659 7213.3
## - weeks:education        1     34402 91364275 7213.4
## - occupation:ethnicity   1     45208 91375080 7213.4
## - occupation:married     1     57552 91387424 7213.5
## - industry:gender        1     61581 91391454 7213.6
## - education:ethnicity    1     62296 91392168 7213.6
## - south:smsa             1     75320 91405193 7213.6
## - weeks:ethnicity        1     75641 91405513 7213.6
## - gender:union           1     78207 91408080 7213.7
## - experience:married     1     90993 91420865 7213.7
## - union:ethnicity        1     93786 91423658 7213.8
## - weeks:south            1     97734 91427607 7213.8
## - experience:union       1    101107 91430979 7213.8
## - weeks:occupation       1    115334 91445207 7213.9
## - experience:gender      1    125634 91455506 7214.0
## - industry:education     1    160208 91490081 7214.2
## - experience:ethnicity   1    182456 91512329 7214.3
## - weeks:smsa             1    196729 91526602 7214.4
## - married:union          1    199085 91528957 7214.4
## - industry:ethnicity     1    202175 91532047 7214.5
## - experience:weeks       1    240350 91570222 7214.7
## - smsa:union             1    277162 91607034 7215.0
## - married:ethnicity      1    280645 91610518 7215.0
## <none>                               91329872 7215.1
## - smsa:gender            1    334544 91664417 7215.3
## - industry:smsa          1    429397 91759269 7215.9
## - experience:occupation  1    441514 91771387 7216.0
## - occupation:union       1    474188 91804060 7216.2
## + smsa:married           1      7707 91322166 7217.1
## + occupation:south       1      3925 91325947 7217.1
## + weeks:union            1      2359 91327513 7217.1
## + gender:education       1      2297 91327576 7217.1
## + south:union            1      2286 91327587 7217.1
## + south:ethnicity        1      1009 91328863 7217.1
## + married:education      1       964 91328908 7217.1
## + experience:south       1       911 91328962 7217.1
## + smsa:education         1       533 91329339 7217.1
## + experience:industry    1       393 91329480 7217.1
## + experience:education   1       192 91329680 7217.1
## + occupation:industry    1        36 91329837 7217.1
## - occupation:education   1    661204 91991077 7217.4
## - gender:ethnicity       1    675499 92005371 7217.5
## - industry:south         1    835478 92165351 7218.6
## - weeks:gender           1    922055 92251927 7219.1
## - industry:union         1   1034239 92364112 7219.8
## - union:education        1   1420257 92750129 7222.3
## - weeks:married          1   1629901 92959773 7223.7
## - south:education        1   1740631 93070503 7224.4
## 
## Step:  AIC=7213.19
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:married + 
##     south:gender + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:gender + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:married          1     18218 91354977 7211.3
## - occupation:gender      1     19000 91355759 7211.3
## - experience:smsa        1     19446 91356206 7211.3
## - occupation:smsa        1     19826 91356585 7211.3
## - married:gender         1     20235 91356994 7211.3
## - smsa:ethnicity         1     21306 91358066 7211.3
## - industry:married       1     21721 91358480 7211.3
## - south:gender           1     25794 91362554 7211.4
## - weeks:education        1     43083 91379842 7211.5
## - occupation:ethnicity   1     47833 91384593 7211.5
## - occupation:married     1     58036 91394796 7211.6
## - education:ethnicity    1     61386 91398146 7211.6
## - industry:gender        1     66112 91402871 7211.6
## - south:smsa             1     75172 91411932 7211.7
## - gender:union           1     77329 91414089 7211.7
## - weeks:ethnicity        1     92263 91429022 7211.8
## - experience:married     1     93796 91430555 7211.8
## - union:ethnicity        1     94576 91431335 7211.8
## - experience:union       1    102818 91439578 7211.9
## - weeks:south            1    109013 91445772 7211.9
## - experience:gender      1    130727 91467487 7212.0
## - weeks:occupation       1    141885 91478644 7212.1
## - industry:education     1    160715 91497474 7212.2
## - experience:ethnicity   1    184771 91521530 7212.4
## - married:union          1    197558 91534318 7212.5
## - industry:ethnicity     1    199423 91536182 7212.5
## - weeks:smsa             1    239991 91576750 7212.8
## - experience:weeks       1    255997 91592757 7212.9
## - smsa:union             1    275402 91612162 7213.0
## - married:ethnicity      1    288277 91625037 7213.1
## <none>                               91336760 7213.2
## - smsa:gender            1    340671 91677431 7213.4
## - industry:smsa          1    434038 91770797 7214.0
## - experience:occupation  1    441980 91778740 7214.1
## - occupation:union       1    468187 91804946 7214.2
## + weeks:industry         1      6887 91329872 7215.1
## + smsa:married           1      6785 91329974 7215.1
## + occupation:south       1      4762 91331998 7215.2
## + weeks:union            1      2387 91334372 7215.2
## + south:union            1      2117 91334643 7215.2
## + gender:education       1      1793 91334967 7215.2
## + experience:south       1      1066 91335693 7215.2
## + south:ethnicity        1       641 91336119 7215.2
## + married:education      1       529 91336231 7215.2
## + smsa:education         1       476 91336283 7215.2
## + experience:education   1       125 91336634 7215.2
## + experience:industry    1       102 91336657 7215.2
## + occupation:industry    1        64 91336696 7215.2
## - occupation:education   1    655228 91991988 7215.4
## - gender:ethnicity       1    688291 92025051 7215.7
## - industry:south         1    828621 92165381 7216.6
## - industry:union         1   1030914 92367673 7217.9
## - weeks:gender           1   1037751 92374511 7217.9
## - union:education        1   1425423 92762183 7220.4
## - weeks:married          1   1681076 93017835 7222.0
## - south:education        1   1737991 93074750 7222.4
## 
## Step:  AIC=7211.31
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:gender + 
##     south:education + smsa:gender + smsa:union + smsa:ethnicity + 
##     married:gender + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:gender           1      8466 91363443 7209.4
## - married:gender         1     14175 91369152 7209.4
## - occupation:smsa        1     17451 91372428 7209.4
## - occupation:gender      1     17785 91372762 7209.4
## - experience:smsa        1     21326 91376304 7209.5
## - industry:married       1     23414 91378392 7209.5
## - smsa:ethnicity         1     23464 91378441 7209.5
## - weeks:education        1     40262 91395239 7209.6
## - occupation:ethnicity   1     44127 91399104 7209.6
## - occupation:married     1     53796 91408773 7209.7
## - education:ethnicity    1     63419 91418397 7209.7
## - gender:union           1     65883 91420860 7209.7
## - industry:gender        1     67062 91422040 7209.7
## - south:smsa             1     68430 91423407 7209.8
## - union:ethnicity        1    100691 91455668 7210.0
## - weeks:ethnicity        1    104000 91458977 7210.0
## - experience:married     1    107638 91462615 7210.0
## - experience:union       1    111593 91466570 7210.0
## - weeks:south            1    119708 91474685 7210.1
## - experience:gender      1    144513 91499490 7210.3
## - weeks:occupation       1    151510 91506487 7210.3
## - industry:education     1    152457 91507434 7210.3
## - married:union          1    179368 91534346 7210.5
## - experience:ethnicity   1    186211 91541188 7210.5
## - industry:ethnicity     1    195886 91550864 7210.6
## - weeks:smsa             1    247851 91602828 7210.9
## - smsa:union             1    262745 91617722 7211.0
## - experience:weeks       1    265322 91620300 7211.0
## - married:ethnicity      1    270866 91625844 7211.1
## <none>                               91354977 7211.3
## - smsa:gender            1    336089 91691066 7211.5
## - industry:smsa          1    422427 91777404 7212.1
## - experience:occupation  1    433262 91788239 7212.1
## - occupation:union       1    466110 91821087 7212.3
## + south:married          1     18218 91336760 7213.2
## + smsa:married           1     10690 91344287 7213.2
## + weeks:industry         1      8525 91346452 7213.3
## + occupation:south       1      4610 91350367 7213.3
## + south:union            1      3105 91351872 7213.3
## + weeks:union            1      2686 91352291 7213.3
## + gender:education       1      2141 91352836 7213.3
## + experience:south       1      2114 91352864 7213.3
## + married:education      1       694 91354283 7213.3
## + smsa:education         1       551 91354426 7213.3
## + experience:industry    1       196 91354781 7213.3
## + south:ethnicity        1       163 91354814 7213.3
## + experience:education   1        71 91354906 7213.3
## + occupation:industry    1         3 91354975 7213.3
## - occupation:education   1    664273 92019250 7213.6
## - gender:ethnicity       1    671907 92026885 7213.7
## - industry:south         1    836437 92191414 7214.7
## - weeks:gender           1   1032352 92387329 7216.0
## - industry:union         1   1037249 92392226 7216.0
## - union:education        1   1421036 92776014 7218.5
## - weeks:married          1   1691530 93046507 7220.2
## - south:education        1   1733563 93088540 7220.5
## 
## Step:  AIC=7209.37
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:gender + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:gender         1     11110 91374554 7207.4
## - occupation:smsa        1     17997 91381441 7207.5
## - experience:smsa        1     20351 91383795 7207.5
## - occupation:gender      1     21238 91384681 7207.5
## - industry:married       1     23339 91386782 7207.5
## - smsa:ethnicity         1     23903 91387346 7207.5
## - weeks:education        1     39669 91403112 7207.6
## - occupation:ethnicity   1     44510 91407954 7207.7
## - occupation:married     1     55041 91418484 7207.7
## - gender:union           1     58337 91421780 7207.7
## - education:ethnicity    1     64554 91427998 7207.8
## - industry:gender        1     65162 91428605 7207.8
## - south:smsa             1     76986 91440430 7207.9
## - union:ethnicity        1    101496 91464939 7208.0
## - weeks:ethnicity        1    107353 91470797 7208.1
## - experience:union       1    109257 91472700 7208.1
## - experience:married     1    109660 91473103 7208.1
## - weeks:south            1    115876 91479319 7208.1
## - experience:gender      1    140512 91503955 7208.3
## - weeks:occupation       1    149829 91513273 7208.3
## - industry:education     1    158477 91521920 7208.4
## - married:union          1    180649 91544092 7208.5
## - experience:ethnicity   1    188171 91551615 7208.6
## - industry:ethnicity     1    199309 91562753 7208.7
## - weeks:smsa             1    249759 91613202 7209.0
## - married:ethnicity      1    266563 91630007 7209.1
## - experience:weeks       1    267124 91630567 7209.1
## - smsa:union             1    272171 91635614 7209.1
## <none>                               91363443 7209.4
## - smsa:gender            1    327972 91691415 7209.5
## - industry:smsa          1    421192 91784636 7210.1
## - experience:occupation  1    440106 91803549 7210.2
## - occupation:union       1    468761 91832204 7210.4
## + smsa:married           1     11110 91352334 7211.3
## + south:gender           1      8466 91354977 7211.3
## + weeks:industry         1      8202 91355242 7211.3
## + occupation:south       1      4074 91359369 7211.3
## + weeks:union            1      2373 91361070 7211.4
## + gender:education       1      2240 91361203 7211.4
## + south:union            1      1056 91362388 7211.4
## + south:ethnicity        1      1003 91362440 7211.4
## + experience:south       1       996 91362447 7211.4
## + south:married          1       890 91362554 7211.4
## + married:education      1       695 91362749 7211.4
## + smsa:education         1       480 91362964 7211.4
## + experience:industry    1       296 91363148 7211.4
## + experience:education   1       241 91363202 7211.4
## + occupation:industry    1         1 91363443 7211.4
## - gender:ethnicity       1    668073 92031516 7211.7
## - occupation:education   1    671651 92035095 7211.7
## - industry:south         1    831462 92194905 7212.8
## - industry:union         1   1029584 92393027 7214.0
## - weeks:gender           1   1049011 92412455 7214.2
## - union:education        1   1414951 92778395 7216.5
## - weeks:married          1   1687582 93051025 7218.3
## - south:education        1   1725340 93088783 7218.5
## 
## Step:  AIC=7207.44
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:gender + occupation:union + 
##     occupation:education + occupation:ethnicity + industry:south + 
##     industry:smsa + industry:married + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + smsa:ethnicity + married:union + 
##     married:ethnicity + gender:union + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:gender      1     17190 91391744 7205.6
## - occupation:smsa        1     17689 91392243 7205.6
## - industry:married       1     19620 91394174 7205.6
## - experience:smsa        1     20354 91394908 7205.6
## - smsa:ethnicity         1     23061 91397614 7205.6
## - weeks:education        1     40111 91414665 7205.7
## - occupation:ethnicity   1     43199 91417753 7205.7
## - occupation:married     1     48815 91423369 7205.8
## - industry:gender        1     59503 91434057 7205.8
## - gender:union           1     59823 91434377 7205.8
## - education:ethnicity    1     65265 91439819 7205.9
## - south:smsa             1     76361 91450915 7205.9
## - experience:married     1    100486 91475040 7206.1
## - union:ethnicity        1    104255 91478809 7206.1
## - weeks:ethnicity        1    105962 91480516 7206.1
## - experience:union       1    108205 91482759 7206.1
## - weeks:south            1    115128 91489682 7206.2
## - experience:gender      1    129407 91503961 7206.3
## - weeks:occupation       1    151336 91525890 7206.4
## - industry:education     1    155555 91530109 7206.5
## - married:union          1    179892 91554446 7206.6
## - experience:ethnicity   1    199356 91573910 7206.7
## - industry:ethnicity     1    202324 91576878 7206.8
## - weeks:smsa             1    249640 91624194 7207.1
## - experience:weeks       1    263359 91637913 7207.2
## - married:ethnicity      1    267315 91641869 7207.2
## - smsa:union             1    271766 91646320 7207.2
## <none>                               91374554 7207.4
## - smsa:gender            1    326210 91700764 7207.6
## - industry:smsa          1    424659 91799212 7208.2
## - experience:occupation  1    445963 91820517 7208.3
## - occupation:union       1    473104 91847658 7208.5
## + smsa:married           1     12281 91362273 7209.4
## + married:gender         1     11110 91363443 7209.4
## + weeks:industry         1      8727 91365827 7209.4
## + south:gender           1      5402 91369152 7209.4
## + occupation:south       1      4195 91370358 7209.4
## + weeks:union            1      2572 91371982 7209.4
## + gender:education       1      1308 91373246 7209.4
## + south:union            1      1104 91373450 7209.4
## + south:ethnicity        1       906 91373648 7209.4
## + south:married          1       777 91373777 7209.4
## + married:education      1       465 91374088 7209.4
## + experience:industry    1       404 91374150 7209.4
## + smsa:education         1       370 91374184 7209.4
## + experience:south       1       363 91374191 7209.4
## + experience:education   1       308 91374246 7209.4
## + occupation:industry    1         7 91374547 7209.4
## - gender:ethnicity       1    663953 92038506 7209.7
## - occupation:education   1    682836 92057390 7209.9
## - industry:south         1    838793 92213347 7210.9
## - industry:union         1   1036826 92411380 7212.2
## - weeks:gender           1   1095032 92469586 7212.5
## - union:education        1   1411066 92785620 7214.6
## - south:education        1   1714230 93088783 7216.5
## - weeks:married          1   1719115 93093669 7216.5
## 
## Step:  AIC=7205.55
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:smsa + 
##     occupation:married + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:married + 
##     industry:gender + industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:smsa        1     17000 91408745 7203.7
## - smsa:ethnicity         1     18606 91410350 7203.7
## - experience:smsa        1     18609 91410353 7203.7
## - industry:married       1     19694 91411438 7203.7
## - occupation:married     1     31806 91423550 7203.8
## - weeks:education        1     40415 91432159 7203.8
## - occupation:ethnicity   1     45014 91436758 7203.8
## - gender:union           1     49392 91441136 7203.9
## - education:ethnicity    1     64206 91455951 7204.0
## - south:smsa             1     75165 91466909 7204.0
## - industry:gender        1     79296 91471040 7204.1
## - experience:married     1     98478 91490222 7204.2
## - union:ethnicity        1    108195 91499939 7204.3
## - weeks:south            1    115300 91507044 7204.3
## - experience:union       1    116056 91507800 7204.3
## - weeks:ethnicity        1    116394 91508138 7204.3
## - experience:gender      1    125855 91517600 7204.4
## - industry:education     1    158734 91550478 7204.6
## - weeks:occupation       1    159956 91551700 7204.6
## - married:union          1    162706 91554450 7204.6
## - industry:ethnicity     1    196886 91588631 7204.8
## - experience:ethnicity   1    197896 91589640 7204.8
## - married:ethnicity      1    259522 91651267 7205.2
## - weeks:smsa             1    262559 91654303 7205.3
## - experience:weeks       1    262864 91654608 7205.3
## - smsa:union             1    269943 91661687 7205.3
## <none>                               91391744 7205.6
## - smsa:gender            1    395113 91786858 7206.1
## - industry:smsa          1    428208 91819952 7206.3
## - experience:occupation  1    440361 91832105 7206.4
## - occupation:union       1    461644 91853388 7206.5
## + occupation:gender      1     17190 91374554 7207.4
## + south:gender           1      8460 91383284 7207.5
## + smsa:married           1      8165 91383580 7207.5
## + gender:education       1      7915 91383830 7207.5
## + married:gender         1      7063 91384681 7207.5
## + weeks:industry         1      6520 91385224 7207.5
## + occupation:south       1      3752 91387992 7207.5
## + weeks:union            1      2382 91389362 7207.5
## + smsa:education         1       488 91391256 7207.5
## + south:union            1       447 91391297 7207.5
## + experience:south       1       406 91391338 7207.5
## + experience:industry    1       374 91391371 7207.5
## + experience:education   1       290 91391454 7207.6
## + south:ethnicity        1       196 91391549 7207.6
## + south:married          1       179 91391566 7207.6
## + occupation:industry    1        91 91391653 7207.6
## + married:education      1        27 91391717 7207.6
## - occupation:education   1    688566 92080311 7208.0
## - gender:ethnicity       1    712771 92104515 7208.2
## - industry:south         1    831919 92223663 7208.9
## - industry:union         1   1069249 92460994 7210.5
## - weeks:gender           1   1183895 92575639 7211.2
## - union:education        1   1453311 92845055 7212.9
## - south:education        1   1702427 93094171 7214.5
## - weeks:married          1   1841478 93233222 7215.4
## 
## Step:  AIC=7203.66
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     smsa:ethnicity + married:union + married:ethnicity + gender:union + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:ethnicity         1     17922 91426666 7201.8
## - industry:married       1     21311 91430055 7201.8
## - experience:smsa        1     21327 91430071 7201.8
## - occupation:married     1     26826 91435571 7201.8
## - weeks:education        1     40725 91449469 7201.9
## - occupation:ethnicity   1     47176 91455920 7202.0
## - gender:union           1     48037 91456782 7202.0
## - education:ethnicity    1     65247 91473991 7202.1
## - south:smsa             1     70116 91478861 7202.1
## - industry:gender        1     81317 91490061 7202.2
## - experience:married     1     95534 91504278 7202.3
## - union:ethnicity        1    109629 91518374 7202.4
## - weeks:south            1    114801 91523545 7202.4
## - weeks:ethnicity        1    116168 91524913 7202.4
## - experience:gender      1    126024 91534769 7202.5
## - experience:union       1    129849 91538593 7202.5
## - industry:education     1    147294 91556038 7202.6
## - married:union          1    156034 91564779 7202.7
## - weeks:occupation       1    156638 91565383 7202.7
## - industry:ethnicity     1    197375 91606120 7202.9
## - experience:ethnicity   1    204894 91613638 7203.0
## - weeks:smsa             1    254546 91663291 7203.3
## - smsa:union             1    258736 91667480 7203.3
## - experience:weeks       1    260946 91669690 7203.4
## - married:ethnicity      1    271129 91679874 7203.4
## <none>                               91408745 7203.7
## - smsa:gender            1    391182 91799926 7204.2
## - industry:smsa          1    411218 91819962 7204.3
## - experience:occupation  1    424247 91832991 7204.4
## - occupation:union       1    501696 91910441 7204.9
## + occupation:smsa        1     17000 91391744 7205.6
## + occupation:gender      1     16502 91392243 7205.6
## + south:gender           1      8949 91399795 7205.6
## + smsa:education         1      8211 91400533 7205.6
## + weeks:industry         1      7107 91401637 7205.6
## + married:gender         1      6893 91401852 7205.6
## + gender:education       1      6706 91402039 7205.6
## + smsa:married           1      6628 91402116 7205.6
## + occupation:south       1      5778 91402967 7205.6
## + weeks:union            1      3385 91405360 7205.6
## + experience:industry    1       637 91408108 7205.7
## + experience:south       1       312 91408433 7205.7
## + experience:education   1       273 91408472 7205.7
## + south:ethnicity        1        88 91408657 7205.7
## + south:married          1        31 91408714 7205.7
## + occupation:industry    1         6 91408738 7205.7
## + married:education      1         6 91408739 7205.7
## + south:union            1         3 91408742 7205.7
## - occupation:education   1    671830 92080574 7206.0
## - gender:ethnicity       1    751230 92159975 7206.5
## - industry:south         1    833714 92242458 7207.1
## - industry:union         1   1127234 92535978 7209.0
## - weeks:gender           1   1177229 92585974 7209.3
## - union:education        1   1471572 92880316 7211.2
## - south:education        1   1691432 93100177 7212.6
## - weeks:married          1   1841985 93250730 7213.5
## 
## Step:  AIC=7201.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:married + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:married       1     21330 91447997 7199.9
## - experience:smsa        1     23495 91450161 7199.9
## - occupation:married     1     24115 91450782 7199.9
## - weeks:education        1     40137 91466804 7200.0
## - gender:union           1     43186 91469852 7200.1
## - occupation:ethnicity   1     57533 91484199 7200.2
## - south:smsa             1     81667 91508333 7200.3
## - industry:gender        1     82997 91509663 7200.3
## - education:ethnicity    1     90616 91517282 7200.4
## - experience:married     1     93930 91520596 7200.4
## - union:ethnicity        1     96936 91523602 7200.4
## - weeks:ethnicity        1    114677 91541343 7200.5
## - weeks:south            1    115965 91542632 7200.5
## - experience:gender      1    121506 91548173 7200.6
## - experience:union       1    126869 91553535 7200.6
## - married:union          1    151534 91578200 7200.8
## - industry:education     1    157328 91583994 7200.8
## - weeks:occupation       1    162502 91589168 7200.8
## - industry:ethnicity     1    190598 91617264 7201.0
## - experience:ethnicity   1    222831 91649497 7201.2
## - weeks:smsa             1    252389 91679056 7201.4
## - experience:weeks       1    260498 91687164 7201.5
## - smsa:union             1    263873 91690539 7201.5
## - married:ethnicity      1    276656 91703322 7201.6
## <none>                               91426666 7201.8
## - smsa:gender            1    382927 91809593 7202.3
## - industry:smsa          1    416465 91843131 7202.5
## - experience:occupation  1    418286 91844952 7202.5
## - occupation:union       1    493523 91920189 7203.0
## + smsa:ethnicity         1     17922 91408745 7203.7
## + occupation:smsa        1     16317 91410350 7203.7
## + occupation:gender      1     12231 91414435 7203.7
## + south:gender           1      8957 91417710 7203.7
## + smsa:married           1      8122 91418545 7203.7
## + occupation:south       1      6856 91419810 7203.7
## + married:gender         1      6742 91419925 7203.7
## + weeks:industry         1      5629 91421037 7203.7
## + smsa:education         1      5004 91421663 7203.7
## + gender:education       1      4790 91421876 7203.7
## + south:ethnicity        1      3558 91423108 7203.8
## + weeks:union            1      3051 91423615 7203.8
## + experience:south       1       701 91425966 7203.8
## + experience:education   1       607 91426060 7203.8
## + experience:industry    1       540 91426126 7203.8
## + south:married          1       123 91426544 7203.8
## + south:union            1        48 91426618 7203.8
## + occupation:industry    1        17 91426649 7203.8
## + married:education      1         1 91426665 7203.8
## - occupation:education   1    671017 92097683 7204.1
## - gender:ethnicity       1    744522 92171188 7204.6
## - industry:south         1    849931 92276598 7205.3
## - industry:union         1   1113062 92539729 7207.0
## - weeks:gender           1   1201990 92628656 7207.6
## - union:education        1   1468439 92895105 7209.3
## - south:education        1   1705058 93131725 7210.8
## - weeks:married          1   1878944 93305610 7211.9
## 
## Step:  AIC=7199.92
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:smsa + experience:married + 
##     experience:gender + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:smsa        1     24165 91472162 7198.1
## - occupation:married     1     25409 91473406 7198.1
## - gender:union           1     36054 91484050 7198.2
## - weeks:education        1     46726 91494723 7198.2
## - occupation:ethnicity   1     58581 91506577 7198.3
## - industry:gender        1     62378 91510374 7198.3
## - experience:married     1     83440 91531436 7198.5
## - south:smsa             1     89891 91537888 7198.5
## - education:ethnicity    1     93833 91541830 7198.5
## - weeks:south            1    107662 91555658 7198.6
## - union:ethnicity        1    108123 91556119 7198.6
## - weeks:ethnicity        1    112078 91560074 7198.6
## - experience:gender      1    114597 91562594 7198.7
## - experience:union       1    128856 91576852 7198.8
## - married:union          1    134849 91582846 7198.8
## - industry:education     1    156138 91604135 7198.9
## - weeks:occupation       1    157658 91605654 7198.9
## - industry:ethnicity     1    181886 91629882 7199.1
## - experience:ethnicity   1    228589 91676585 7199.4
## - weeks:smsa             1    246640 91694637 7199.5
## - experience:weeks       1    252860 91700856 7199.6
## - smsa:union             1    255258 91703254 7199.6
## - married:ethnicity      1    267567 91715564 7199.7
## <none>                               91447997 7199.9
## - smsa:gender            1    385844 91833841 7200.4
## - experience:occupation  1    412439 91860436 7200.6
## - industry:smsa          1    438254 91886251 7200.8
## - occupation:union       1    488114 91936111 7201.1
## + industry:married       1     21330 91426666 7201.8
## + smsa:ethnicity         1     17941 91430055 7201.8
## + occupation:smsa        1     17902 91430095 7201.8
## + occupation:gender      1     12267 91435730 7201.8
## + south:gender           1      9518 91438479 7201.9
## + occupation:south       1      6703 91441293 7201.9
## + weeks:industry         1      5619 91442378 7201.9
## + smsa:education         1      5367 91442629 7201.9
## + gender:education       1      5004 91442993 7201.9
## + smsa:married           1      4786 91443210 7201.9
## + south:ethnicity        1      4661 91443336 7201.9
## + married:gender         1      3871 91444126 7201.9
## + weeks:union            1      3798 91444199 7201.9
## + experience:education   1       867 91447129 7201.9
## + married:education      1       533 91447464 7201.9
## + experience:south       1       504 91447492 7201.9
## + south:married          1       241 91447756 7201.9
## + south:union            1       227 91447769 7201.9
## + experience:industry    1        83 91447913 7201.9
## + occupation:industry    1        44 91447952 7201.9
## - occupation:education   1    658867 92106864 7202.2
## - gender:ethnicity       1    735763 92183759 7202.7
## - industry:south         1    855705 92303701 7203.5
## - industry:union         1   1099695 92547692 7205.0
## - weeks:gender           1   1216197 92664194 7205.8
## - union:education        1   1465201 92913197 7207.4
## - south:education        1   1690266 93138262 7208.8
## - weeks:married          1   1911054 93359051 7210.2
## 
## Step:  AIC=7198.08
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:married + 
##     occupation:union + occupation:education + occupation:ethnicity + 
##     industry:south + industry:smsa + industry:gender + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:union + gender:ethnicity + union:education + union:ethnicity + 
##     education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:married     1     27214 91499376 7196.3
## - gender:union           1     36173 91508335 7196.3
## - weeks:education        1     47415 91519577 7196.4
## - occupation:ethnicity   1     58633 91530795 7196.5
## - industry:gender        1     60377 91532539 7196.5
## - experience:married     1     89620 91561782 7196.7
## - south:smsa             1     92373 91564535 7196.7
## - education:ethnicity    1     95426 91567588 7196.7
## - union:ethnicity        1    104033 91576195 7196.8
## - experience:gender      1    107012 91579174 7196.8
## - weeks:south            1    107629 91579791 7196.8
## - weeks:ethnicity        1    113805 91585967 7196.8
## - experience:union       1    118126 91590287 7196.8
## - married:union          1    134116 91606278 7196.9
## - industry:education     1    150156 91622317 7197.1
## - weeks:occupation       1    153588 91625750 7197.1
## - industry:ethnicity     1    179847 91652008 7197.2
## - experience:ethnicity   1    218699 91690860 7197.5
## - experience:weeks       1    241028 91713189 7197.6
## - weeks:smsa             1    260665 91732826 7197.8
## - married:ethnicity      1    263929 91736090 7197.8
## - smsa:union             1    266964 91739126 7197.8
## <none>                               91472162 7198.1
## - industry:smsa          1    423052 91895214 7198.8
## - smsa:gender            1    435613 91907775 7198.9
## - experience:occupation  1    462201 91934363 7199.1
## - occupation:union       1    483054 91955215 7199.2
## + experience:smsa        1     24165 91447997 7199.9
## + industry:married       1     22001 91450161 7199.9
## + occupation:smsa        1     20862 91451299 7199.9
## + smsa:ethnicity         1     20143 91452018 7199.9
## + smsa:education         1     11938 91460223 7200.0
## + occupation:gender      1     10355 91461807 7200.0
## + south:gender           1      8255 91463907 7200.0
## + smsa:married           1      6948 91465213 7200.0
## + occupation:south       1      6291 91465871 7200.0
## + weeks:industry         1      5786 91466376 7200.0
## + south:ethnicity        1      5765 91466397 7200.0
## + gender:education       1      4523 91467638 7200.0
## + married:gender         1      3963 91468199 7200.0
## + experience:south       1      2984 91469178 7200.1
## + experience:education   1      2965 91469196 7200.1
## + weeks:union            1      1513 91470649 7200.1
## + married:education      1       723 91471438 7200.1
## + south:married          1       645 91471516 7200.1
## + south:union            1       222 91471939 7200.1
## + occupation:industry    1        76 91472086 7200.1
## + experience:industry    1        37 91472124 7200.1
## - occupation:education   1    655183 92127344 7200.3
## - gender:ethnicity       1    728809 92200971 7200.8
## - industry:south         1    866006 92338168 7201.7
## - industry:union         1   1126718 92598879 7203.4
## - weeks:gender           1   1230469 92702630 7204.0
## - union:education        1   1461939 92934101 7205.5
## - south:education        1   1668715 93140876 7206.8
## - weeks:married          1   1915526 93387688 7208.4
## 
## Step:  AIC=7196.25
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:union + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - gender:union           1     24521 91523897 7194.4
## - industry:gender        1     42492 91541868 7194.5
## - occupation:ethnicity   1     45483 91544859 7194.5
## - weeks:education        1     46152 91545528 7194.6
## - experience:married     1     81562 91580938 7194.8
## - south:smsa             1     91839 91591215 7194.8
## - education:ethnicity    1     95964 91595340 7194.9
## - experience:gender      1    106367 91605743 7194.9
## - married:union          1    108704 91608080 7195.0
## - weeks:south            1    111022 91610398 7195.0
## - union:ethnicity        1    116632 91616007 7195.0
## - weeks:ethnicity        1    121637 91621013 7195.0
## - experience:union       1    121697 91621073 7195.0
## - industry:education     1    144126 91643502 7195.2
## - weeks:occupation       1    150637 91650013 7195.2
## - industry:ethnicity     1    194053 91693429 7195.5
## - experience:ethnicity   1    219638 91719014 7195.7
## - experience:weeks       1    251198 91750574 7195.9
## - married:ethnicity      1    255197 91754573 7195.9
## - smsa:union             1    261403 91760778 7195.9
## - weeks:smsa             1    262530 91761906 7196.0
## <none>                               91499376 7196.3
## - smsa:gender            1    408406 91907782 7196.9
## - industry:smsa          1    418526 91917902 7197.0
## - experience:occupation  1    436101 91935477 7197.1
## - occupation:union       1    521804 92021180 7197.6
## + occupation:married     1     27214 91472162 7198.1
## + experience:smsa        1     25970 91473406 7198.1
## + industry:married       1     23388 91475988 7198.1
## + smsa:ethnicity         1     17176 91482200 7198.1
## + occupation:smsa        1     15460 91483916 7198.2
## + married:education      1     14462 91484914 7198.2
## + smsa:education         1     11526 91487849 7198.2
## + weeks:industry         1      7994 91491382 7198.2
## + south:ethnicity        1      7971 91491405 7198.2
## + south:gender           1      6602 91492773 7198.2
## + occupation:south       1      5536 91493840 7198.2
## + experience:south       1      4787 91494589 7198.2
## + smsa:married           1      3312 91496064 7198.2
## + married:gender         1      2524 91496851 7198.2
## + experience:education   1      2480 91496895 7198.2
## + weeks:union            1      2313 91497063 7198.2
## + south:married          1       741 91498635 7198.2
## + occupation:gender      1       703 91498673 7198.2
## + occupation:industry    1       410 91498966 7198.2
## + gender:education       1       222 91499154 7198.3
## + south:union            1       218 91499158 7198.3
## + experience:industry    1       180 91499196 7198.3
## - occupation:education   1    641790 92141165 7198.4
## - gender:ethnicity       1    702233 92201609 7198.8
## - industry:south         1    878094 92377470 7199.9
## - industry:union         1   1142034 92641410 7201.6
## - weeks:gender           1   1251927 92751303 7202.3
## - union:education        1   1448332 92947708 7203.6
## - south:education        1   1669678 93169054 7205.0
## - weeks:married          1   2039461 93538837 7207.4
## 
## Step:  AIC=7194.41
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:gender + 
##     industry:union + industry:education + industry:ethnicity + 
##     south:smsa + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:gender        1     36721 91560617 7192.7
## - weeks:education        1     41723 91565619 7192.7
## - occupation:ethnicity   1     42898 91566794 7192.7
## - experience:married     1     83163 91607059 7193.0
## - south:smsa             1     84850 91608747 7193.0
## - married:union          1     88831 91612728 7193.0
## - education:ethnicity    1    100274 91624171 7193.1
## - experience:gender      1    108851 91632748 7193.1
## - union:ethnicity        1    116030 91639926 7193.2
## - weeks:south            1    119829 91643726 7193.2
## - weeks:ethnicity        1    123414 91647311 7193.2
## - experience:union       1    132488 91656385 7193.3
## - industry:education     1    134493 91658390 7193.3
## - weeks:occupation       1    157170 91681067 7193.4
## - industry:ethnicity     1    182444 91706341 7193.6
## - experience:ethnicity   1    233535 91757432 7193.9
## - experience:weeks       1    250494 91774391 7194.0
## - married:ethnicity      1    251663 91775559 7194.0
## - smsa:union             1    263067 91786963 7194.1
## - weeks:smsa             1    268040 91791937 7194.2
## <none>                               91523897 7194.4
## - smsa:gender            1    422425 91946322 7195.2
## - industry:smsa          1    422686 91946583 7195.2
## - experience:occupation  1    428356 91952253 7195.2
## - occupation:union       1    528811 92052707 7195.8
## + experience:smsa        1     25658 91498239 7196.2
## + gender:union           1     24521 91499376 7196.3
## + industry:married       1     16559 91507337 7196.3
## + occupation:married     1     15562 91508335 7196.3
## + occupation:smsa        1     15407 91508490 7196.3
## + smsa:ethnicity         1     13973 91509923 7196.3
## + south:ethnicity        1     10491 91513406 7196.3
## + smsa:education         1      9753 91514143 7196.3
## + weeks:industry         1      7327 91516569 7196.4
## + married:education      1      6789 91517108 7196.4
## + occupation:south       1      5879 91518017 7196.4
## + experience:south       1      5550 91518346 7196.4
## + married:gender         1      4293 91519604 7196.4
## + smsa:married           1      3430 91520467 7196.4
## + experience:education   1      2337 91521560 7196.4
## + south:married          1      1225 91522672 7196.4
## + south:gender           1      1211 91522685 7196.4
## + weeks:union            1      1097 91522800 7196.4
## + occupation:gender      1       784 91523113 7196.4
## + occupation:industry    1       650 91523247 7196.4
## + gender:education       1       645 91523251 7196.4
## + south:union            1       519 91523377 7196.4
## + experience:industry    1       420 91523477 7196.4
## - occupation:education   1    630567 92154463 7196.5
## - gender:ethnicity       1    697487 92221384 7196.9
## - industry:south         1    887674 92411570 7198.2
## - industry:union         1   1146934 92670831 7199.8
## - weeks:gender           1   1281983 92805880 7200.7
## - union:education        1   1491022 93014919 7202.0
## - south:education        1   1671819 93195716 7203.2
## - weeks:married          1   2026020 93549916 7205.4
## 
## Step:  AIC=7192.65
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:education + weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:education        1     43059 91603677 7190.9
## - occupation:ethnicity   1     45270 91605887 7190.9
## - education:ethnicity    1     82150 91642767 7191.2
## - experience:married     1     82402 91643020 7191.2
## - south:smsa             1     86945 91647563 7191.2
## - experience:gender      1     91359 91651976 7191.2
## - married:union          1    100244 91660862 7191.3
## - union:ethnicity        1    117665 91678282 7191.4
## - experience:union       1    121657 91682274 7191.4
## - weeks:ethnicity        1    122983 91683600 7191.4
## - industry:education     1    126738 91687355 7191.5
## - weeks:south            1    127391 91688009 7191.5
## - weeks:occupation       1    160971 91721588 7191.7
## - experience:weeks       1    239281 91799899 7192.2
## - married:ethnicity      1    242734 91803351 7192.2
## - experience:ethnicity   1    242879 91803496 7192.2
## - industry:ethnicity     1    253952 91814569 7192.3
## - weeks:smsa             1    268091 91828708 7192.4
## - smsa:union             1    276719 91837336 7192.4
## <none>                               91560617 7192.7
## - industry:smsa          1    406681 91967298 7193.3
## - smsa:gender            1    430952 91991570 7193.4
## - experience:occupation  1    438906 91999523 7193.5
## - occupation:union       1    525486 92086103 7194.1
## + industry:gender        1     36721 91523897 7194.4
## + experience:smsa        1     23331 91537287 7194.5
## + gender:union           1     18749 91541868 7194.5
## + occupation:smsa        1     17156 91543461 7194.5
## + smsa:ethnicity         1     16453 91544165 7194.5
## + weeks:industry         1      9780 91550837 7194.6
## + smsa:education         1      9543 91551074 7194.6
## + south:ethnicity        1      7224 91553393 7194.6
## + occupation:south       1      6227 91554390 7194.6
## + experience:south       1      4940 91555677 7194.6
## + occupation:married     1      4678 91555940 7194.6
## + married:education      1      4631 91555986 7194.6
## + smsa:married           1      3721 91556896 7194.6
## + gender:education       1      2662 91557955 7194.6
## + occupation:gender      1      2498 91558120 7194.6
## + experience:education   1      2241 91558377 7194.6
## + married:gender         1      2144 91558473 7194.6
## + occupation:industry    1      2045 91558572 7194.6
## + south:gender           1      1924 91558693 7194.6
## + south:married          1      1078 91559539 7194.6
## + experience:industry    1       716 91559902 7194.6
## + weeks:union            1       427 91560190 7194.6
## + south:union            1       412 91560206 7194.6
## + industry:married       1       111 91560506 7194.6
## - occupation:education   1    639533 92200150 7194.8
## - gender:ethnicity       1    708776 92269393 7195.2
## - industry:south         1    895404 92456021 7196.4
## - industry:union         1   1188027 92748644 7198.3
## - weeks:gender           1   1350715 92911332 7199.4
## - union:education        1   1464888 93025505 7200.1
## - south:education        1   1685709 93246326 7201.5
## - weeks:married          1   2063089 93623706 7203.9
## 
## Step:  AIC=7190.93
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     occupation:ethnicity + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - occupation:ethnicity   1     42650 91646326 7189.2
## - experience:married     1     79377 91683054 7189.4
## - experience:gender      1     80236 91683912 7189.5
## - education:ethnicity    1     82696 91686373 7189.5
## - south:smsa             1     94496 91698172 7189.5
## - weeks:ethnicity        1    100938 91704615 7189.6
## - married:union          1    107272 91710949 7189.6
## - union:ethnicity        1    109104 91712780 7189.6
## - industry:education     1    120659 91724336 7189.7
## - experience:union       1    123666 91727343 7189.7
## - weeks:south            1    161510 91765187 7190.0
## - married:ethnicity      1    229487 91833164 7190.4
## - experience:ethnicity   1    240756 91844433 7190.5
## - industry:ethnicity     1    245801 91849478 7190.5
## - weeks:smsa             1    249703 91853379 7190.5
## - experience:weeks       1    267405 91871082 7190.7
## - smsa:union             1    271958 91875635 7190.7
## <none>                               91603677 7190.9
## - industry:smsa          1    409391 92013068 7191.6
## - experience:occupation  1    437316 92040993 7191.8
## - smsa:gender            1    444810 92048486 7191.8
## - occupation:union       1    507879 92111556 7192.2
## - weeks:occupation       1    527801 92131478 7192.3
## + weeks:education        1     43059 91560617 7192.7
## + industry:gender        1     38058 91565619 7192.7
## + experience:smsa        1     23923 91579754 7192.8
## + weeks:industry         1     19550 91584126 7192.8
## + occupation:smsa        1     17912 91585765 7192.8
## + smsa:ethnicity         1     16307 91587370 7192.8
## + gender:union           1     14790 91588887 7192.8
## + smsa:education         1      9067 91594609 7192.9
## + occupation:south       1      8745 91594931 7192.9
## + experience:south       1      6426 91597250 7192.9
## + gender:education       1      5619 91598058 7192.9
## + occupation:married     1      4516 91599160 7192.9
## + south:ethnicity        1      4447 91599230 7192.9
## + married:education      1      3676 91600001 7192.9
## + smsa:married           1      3572 91600104 7192.9
## + occupation:gender      1      2982 91600695 7192.9
## + south:gender           1      2049 91601628 7192.9
## + married:gender         1      1936 91601741 7192.9
## - occupation:education   1    616286 92219963 7192.9
## + experience:education   1      1278 91602399 7192.9
## + weeks:union            1      1203 91602474 7192.9
## + south:married          1       733 91602943 7192.9
## + occupation:industry    1       649 91603028 7192.9
## + experience:industry    1       140 91603536 7192.9
## + south:union            1        92 91603585 7192.9
## + industry:married       1        33 91603643 7192.9
## - gender:ethnicity       1    680823 92284500 7193.3
## - industry:south         1    893102 92496779 7194.7
## - industry:union         1   1192834 92796511 7196.6
## - weeks:gender           1   1327694 92931371 7197.5
## - union:education        1   1606155 93209831 7199.3
## - south:education        1   1746342 93350019 7200.2
## - weeks:married          1   2058363 93662040 7202.2
## 
## Step:  AIC=7189.21
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:gender + 
##     experience:union + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:gender      1     72569 91718895 7187.7
## - experience:married     1     75522 91721848 7187.7
## - weeks:ethnicity        1     99007 91745334 7187.8
## - south:smsa             1    100726 91747053 7187.9
## - married:union          1    109839 91756165 7187.9
## - experience:union       1    111212 91757538 7187.9
## - industry:education     1    119017 91765344 7188.0
## - union:ethnicity        1    158709 91805036 7188.2
## - weeks:south            1    165021 91811347 7188.3
## - education:ethnicity    1    197883 91844209 7188.5
## - weeks:smsa             1    245643 91891969 7188.8
## - industry:ethnicity     1    253128 91899455 7188.8
## - experience:weeks       1    259416 91905742 7188.9
## - smsa:union             1    262957 91909283 7188.9
## - experience:ethnicity   1    263720 91910046 7188.9
## - married:ethnicity      1    277158 91923484 7189.0
## <none>                               91646326 7189.2
## - industry:smsa          1    400475 92046801 7189.8
## - smsa:gender            1    434402 92080728 7190.0
## - experience:occupation  1    462841 92109168 7190.2
## - weeks:occupation       1    546883 92193209 7190.7
## - occupation:union       1    568327 92214654 7190.9
## + occupation:ethnicity   1     42650 91603677 7190.9
## + weeks:education        1     40439 91605887 7190.9
## + industry:gender        1     40358 91605969 7190.9
## + smsa:ethnicity         1     25827 91620500 7191.0
## + experience:smsa        1     23434 91622892 7191.1
## + occupation:smsa        1     21339 91624987 7191.1
## + weeks:industry         1     21274 91625053 7191.1
## + gender:union           1     12792 91633535 7191.1
## + occupation:gender      1      6863 91639463 7191.2
## + smsa:education         1      6641 91639685 7191.2
## + experience:south       1      5934 91640392 7191.2
## + smsa:married           1      5663 91640663 7191.2
## + occupation:south       1      4603 91641724 7191.2
## + south:ethnicity        1      3830 91642497 7191.2
## + gender:education       1      3671 91642655 7191.2
## + married:education      1      3660 91642667 7191.2
## + south:gender           1      2944 91643382 7191.2
## + married:gender         1      1428 91644898 7191.2
## + weeks:union            1      1329 91644997 7191.2
## + experience:education   1       818 91645509 7191.2
## + occupation:married     1       732 91645594 7191.2
## + occupation:industry    1       555 91645771 7191.2
## + south:married          1       226 91646100 7191.2
## + industry:married       1        18 91646309 7191.2
## + experience:industry    1        16 91646310 7191.2
## + south:union            1         4 91646322 7191.2
## - occupation:education   1    669547 92315874 7191.5
## - gender:ethnicity       1    907631 92553957 7193.1
## - industry:south         1    915075 92561401 7193.1
## - industry:union         1   1211283 92857609 7195.0
## - weeks:gender           1   1356513 93002839 7195.9
## - union:education        1   1565748 93212074 7197.3
## - south:education        1   1759145 93405471 7198.5
## - weeks:married          1   2074217 93720543 7200.5
## 
## Step:  AIC=7187.68
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:married + experience:union + 
##     experience:ethnicity + weeks:occupation + weeks:south + weeks:smsa + 
##     weeks:married + weeks:gender + weeks:ethnicity + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:education + industry:ethnicity + south:smsa + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:married     1     16454 91735349 7185.8
## - weeks:ethnicity        1     92318 91811213 7186.3
## - south:smsa             1     97940 91816835 7186.3
## - experience:union       1     99672 91818567 7186.3
## - married:union          1    109224 91828120 7186.4
## - industry:education     1    115167 91834063 7186.4
## - union:ethnicity        1    151502 91870397 7186.7
## - weeks:south            1    172388 91891283 7186.8
## - education:ethnicity    1    200577 91919472 7187.0
## - experience:weeks       1    240431 91959326 7187.2
## - industry:ethnicity     1    249329 91968224 7187.3
## - weeks:smsa             1    259857 91978752 7187.4
## - smsa:union             1    266700 91985595 7187.4
## <none>                               91718895 7187.7
## - married:ethnicity      1    364918 92083813 7188.0
## - experience:ethnicity   1    381676 92100571 7188.1
## - industry:smsa          1    400833 92119728 7188.3
## - experience:occupation  1    454555 92173450 7188.6
## - smsa:gender            1    492970 92211866 7188.9
## + experience:gender      1     72569 91646326 7189.2
## - weeks:occupation       1    546974 92265870 7189.2
## + occupation:ethnicity   1     34983 91683912 7189.5
## + weeks:education        1     30361 91688534 7189.5
## + weeks:industry         1     25373 91693522 7189.5
## + industry:gender        1     23065 91695831 7189.5
## - occupation:union       1    598093 92316988 7189.5
## + occupation:smsa        1     20001 91698894 7189.5
## + smsa:ethnicity         1     19390 91699506 7189.6
## + experience:smsa        1     17469 91701427 7189.6
## + gender:union           1     16021 91702875 7189.6
## + smsa:married           1      6920 91711975 7189.6
## + smsa:education         1      6754 91712142 7189.6
## + south:ethnicity        1      5242 91713653 7189.6
## + experience:south       1      4540 91714356 7189.6
## + occupation:south       1      4119 91714777 7189.7
## + occupation:gender      1      3218 91715678 7189.7
## + south:married          1      2965 91715930 7189.7
## + gender:education       1      2569 91716326 7189.7
## + married:education      1      2192 91716703 7189.7
## + south:gender           1      1813 91717083 7189.7
## + occupation:married     1      1597 91717299 7189.7
## + experience:education   1      1514 91717381 7189.7
## + weeks:union            1       834 91718062 7189.7
## + married:gender         1       760 91718135 7189.7
## + occupation:industry    1       158 91718738 7189.7
## + industry:married       1       139 91718757 7189.7
## + south:union            1       135 91718760 7189.7
## + experience:industry    1         5 91718891 7189.7
## - occupation:education   1    679627 92398523 7190.1
## - industry:south         1    921381 92640276 7191.6
## - gender:ethnicity       1    959436 92678331 7191.9
## - industry:union         1   1251005 92969901 7193.7
## - weeks:gender           1   1443342 93162237 7195.0
## - union:education        1   1557988 93276884 7195.7
## - south:education        1   1725950 93444846 7196.8
## - weeks:married          1   2076553 93795448 7199.0
## 
## Step:  AIC=7185.78
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + weeks:ethnicity + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:ethnicity        1     95528 91830877 7184.4
## - south:smsa             1     96442 91831791 7184.4
## - experience:union       1    106702 91842051 7184.5
## - industry:education     1    114288 91849637 7184.5
## - married:union          1    116096 91851445 7184.5
## - union:ethnicity        1    150001 91885350 7184.8
## - weeks:south            1    175557 91910906 7184.9
## - education:ethnicity    1    198063 91933412 7185.1
## - experience:weeks       1    249558 91984907 7185.4
## - industry:ethnicity     1    254155 91989504 7185.4
## - weeks:smsa             1    263816 91999165 7185.5
## - smsa:union             1    266458 92001807 7185.5
## <none>                               91735349 7185.8
## - married:ethnicity      1    363824 92099173 7186.1
## - experience:ethnicity   1    365607 92100956 7186.2
## - industry:smsa          1    398609 92133958 7186.4
## - experience:occupation  1    442613 92177962 7186.6
## - smsa:gender            1    478939 92214288 7186.9
## - weeks:occupation       1    541037 92276386 7187.3
## + occupation:ethnicity   1     35780 91699569 7187.6
## + weeks:education        1     32647 91702702 7187.6
## + industry:gender        1     28319 91707030 7187.6
## - occupation:union       1    591791 92327140 7187.6
## + weeks:industry         1     25930 91709419 7187.6
## + experience:smsa        1     22386 91712963 7187.6
## + smsa:ethnicity         1     20979 91714370 7187.6
## + occupation:smsa        1     19029 91716320 7187.7
## + experience:married     1     16454 91718895 7187.7
## + gender:union           1     15489 91719860 7187.7
## + experience:gender      1     13501 91721848 7187.7
## + smsa:married           1      8802 91726547 7187.7
## + smsa:education         1      5949 91729400 7187.7
## + occupation:gender      1      5129 91730220 7187.8
## + experience:south       1      4458 91730891 7187.8
## + south:ethnicity        1      4035 91731314 7187.8
## + gender:education       1      3940 91731409 7187.8
## + occupation:south       1      3594 91731755 7187.8
## + south:gender           1      3094 91732255 7187.8
## + south:married          1      2769 91732580 7187.8
## + experience:education   1      1972 91733377 7187.8
## + married:gender         1       683 91734666 7187.8
## + weeks:union            1       672 91734677 7187.8
## + married:education      1       474 91734875 7187.8
## + south:union            1       470 91734879 7187.8
## + occupation:married     1       428 91734921 7187.8
## + occupation:industry    1       120 91735229 7187.8
## + industry:married       1       117 91735232 7187.8
## + experience:industry    1        30 91735319 7187.8
## - occupation:education   1    671217 92406566 7188.1
## - industry:south         1    914177 92649526 7189.7
## - gender:ethnicity       1   1006255 92741604 7190.3
## - industry:union         1   1249393 92984742 7191.8
## - weeks:gender           1   1432607 93167956 7193.0
## - union:education        1   1569011 93304360 7193.9
## - south:education        1   1765487 93500835 7195.1
## - weeks:married          1   2107284 93842633 7197.3
## 
## Step:  AIC=7184.4
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:smsa + south:education + smsa:gender + 
##     smsa:union + married:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - south:smsa             1    103010 91933887 7183.1
## - experience:union       1    115246 91946123 7183.2
## - industry:education     1    116429 91947305 7183.2
## - weeks:south            1    142527 91973404 7183.3
## - married:union          1    147018 91977894 7183.4
## - education:ethnicity    1    156891 91987768 7183.4
## - union:ethnicity        1    161875 91992752 7183.5
## - weeks:smsa             1    213391 92044267 7183.8
## - smsa:union             1    251891 92082768 7184.0
## - experience:weeks       1    285255 92116131 7184.2
## - industry:ethnicity     1    293587 92124463 7184.3
## <none>                               91830877 7184.4
## - industry:smsa          1    402100 92232976 7185.0
## - experience:ethnicity   1    434621 92265498 7185.2
## - experience:occupation  1    444932 92275809 7185.3
## - weeks:occupation       1    480674 92311550 7185.5
## - smsa:gender            1    483644 92314520 7185.5
## + weeks:ethnicity        1     95528 91735349 7185.8
## - married:ethnicity      1    525658 92356535 7185.8
## + weeks:industry         1     48637 91782240 7186.1
## + occupation:ethnicity   1     34456 91796420 7186.2
## - occupation:union       1    585617 92416494 7186.2
## + industry:gender        1     28915 91801962 7186.2
## + experience:smsa        1     24827 91806049 7186.2
## + experience:married     1     19663 91811213 7186.3
## + smsa:ethnicity         1     19350 91811527 7186.3
## + occupation:smsa        1     17861 91813016 7186.3
## + gender:union           1     17696 91813181 7186.3
## + weeks:education        1     15030 91815847 7186.3
## + experience:gender      1      9705 91821172 7186.3
## + occupation:gender      1      6941 91823935 7186.4
## + occupation:south       1      6802 91824075 7186.4
## + smsa:married           1      5945 91824931 7186.4
## + south:gender           1      5564 91825313 7186.4
## + smsa:education         1      5476 91825401 7186.4
## + gender:education       1      4229 91826647 7186.4
## + south:married          1      4187 91826689 7186.4
## + weeks:union            1      4143 91826734 7186.4
## + experience:south       1      3475 91827402 7186.4
## + married:education      1      3315 91827562 7186.4
## + experience:education   1      3136 91827741 7186.4
## + south:ethnicity        1      3025 91827852 7186.4
## + occupation:married     1      1387 91829490 7186.4
## + married:gender         1      1093 91829784 7186.4
## + south:union            1       836 91830041 7186.4
## + industry:married       1       573 91830304 7186.4
## + occupation:industry    1        89 91830788 7186.4
## + experience:industry    1        17 91830860 7186.4
## - occupation:education   1    701610 92532486 7186.9
## - industry:south         1    901076 92731952 7188.2
## - gender:ethnicity       1   1165336 92996213 7189.9
## - industry:union         1   1272939 93103816 7190.6
## - weeks:gender           1   1400635 93231511 7191.4
## - union:education        1   1589922 93420799 7192.6
## - south:education        1   1710976 93541853 7193.4
## - weeks:married          1   2028010 93858886 7195.4
## 
## Step:  AIC=7183.07
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:education + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:union + married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - industry:education     1    106680 92040567 7181.8
## - experience:union       1    111457 92045344 7181.8
## - married:union          1    138956 92072843 7182.0
## - education:ethnicity    1    159058 92092945 7182.1
## - weeks:south            1    164273 92098160 7182.1
## - union:ethnicity        1    177437 92111324 7182.2
## - weeks:smsa             1    209244 92143131 7182.4
## - smsa:union             1    223837 92157724 7182.5
## - experience:weeks       1    276077 92209964 7182.9
## - industry:ethnicity     1    276553 92210440 7182.9
## <none>                               91933887 7183.1
## - industry:smsa          1    367198 92301085 7183.4
## - experience:occupation  1    445661 92379548 7183.9
## - experience:ethnicity   1    458102 92391989 7184.0
## - smsa:gender            1    485151 92419038 7184.2
## - weeks:occupation       1    496360 92430247 7184.3
## + south:smsa             1    103010 91830877 7184.4
## + weeks:ethnicity        1    102096 91831791 7184.4
## - occupation:union       1    534379 92468266 7184.5
## - married:ethnicity      1    560383 92494270 7184.7
## + weeks:industry         1     48465 91885422 7184.8
## + occupation:ethnicity   1     40202 91893685 7184.8
## + smsa:ethnicity         1     34553 91899335 7184.8
## + industry:gender        1     31191 91902696 7184.9
## + experience:smsa        1     27367 91906520 7184.9
## + weeks:education        1     19184 91914703 7184.9
## + experience:married     1     18081 91915806 7185.0
## + south:gender           1     15550 91918337 7185.0
## + occupation:smsa        1     12253 91921634 7185.0
## + gender:union           1     10861 91923026 7185.0
## + experience:gender      1      9608 91924279 7185.0
## + smsa:married           1      8056 91925832 7185.0
## + weeks:union            1      6852 91927035 7185.0
## + occupation:gender      1      6693 91927194 7185.0
## + experience:south       1      5166 91928721 7185.0
## + married:education      1      4852 91929035 7185.0
## + experience:education   1      4460 91929428 7185.0
## + gender:education       1      3208 91930679 7185.1
## + occupation:south       1      1977 91931910 7185.1
## + married:gender         1      1754 91932133 7185.1
## + occupation:married     1      1448 91932439 7185.1
## + smsa:education         1       889 91932998 7185.1
## + south:union            1       869 91933018 7185.1
## + experience:industry    1       238 91933649 7185.1
## + south:married          1       112 91933776 7185.1
## + occupation:industry    1        53 91933834 7185.1
## + south:ethnicity        1        34 91933853 7185.1
## + industry:married       1         0 91933887 7185.1
## - occupation:education   1    701448 92635335 7185.6
## - industry:south         1    894743 92828630 7186.8
## - gender:ethnicity       1   1165663 93099550 7188.6
## - industry:union         1   1315146 93249033 7189.5
## - weeks:gender           1   1379536 93313423 7189.9
## - union:education        1   1677202 93611089 7191.8
## - weeks:married          1   2008907 93942794 7193.9
## - south:education        1   2072779 94006666 7194.3
## 
## Step:  AIC=7181.76
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:union + experience:ethnicity + 
##     weeks:occupation + weeks:south + weeks:smsa + weeks:married + 
##     weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - experience:union       1    103702 92144269 7180.4
## - married:union          1    136786 92177353 7180.6
## - education:ethnicity    1    175203 92215770 7180.9
## - weeks:south            1    181940 92222507 7180.9
## - union:ethnicity        1    199964 92240531 7181.1
## - weeks:smsa             1    227771 92268338 7181.2
## - smsa:union             1    239666 92280233 7181.3
## - industry:ethnicity     1    242738 92283305 7181.3
## - experience:weeks       1    269710 92310277 7181.5
## - industry:smsa          1    308384 92348951 7181.8
## <none>                               92040567 7181.8
## - experience:ethnicity   1    467579 92508146 7182.8
## - smsa:gender            1    495308 92535875 7183.0
## - experience:occupation  1    502898 92543465 7183.0
## + industry:education     1    106680 91933887 7183.1
## + weeks:ethnicity        1    103892 91936675 7183.1
## + south:smsa             1     93262 91947305 7183.2
## - married:ethnicity      1    551338 92591905 7183.3
## - weeks:occupation       1    570022 92610589 7183.4
## - occupation:union       1    571383 92611951 7183.4
## + smsa:ethnicity         1     44663 91995905 7183.5
## + weeks:industry         1     44539 91996028 7183.5
## + occupation:ethnicity   1     38568 92001999 7183.5
## + occupation:industry    1     31035 92009532 7183.6
## + industry:gender        1     24797 92015771 7183.6
## + south:gender           1     23950 92016617 7183.6
## + experience:smsa        1     21932 92018635 7183.6
## + experience:married     1     17295 92023272 7183.6
## - occupation:education   1    604540 92645107 7183.7
## + weeks:education        1     15330 92025238 7183.7
## + gender:education       1     10685 92029883 7183.7
## + experience:gender      1      9008 92031559 7183.7
## + experience:education   1      8517 92032050 7183.7
## + occupation:gender      1      7975 92032592 7183.7
## + weeks:union            1      6314 92034253 7183.7
## + smsa:married           1      6246 92034322 7183.7
## + gender:union           1      6108 92034459 7183.7
## + occupation:smsa        1      4023 92036544 7183.7
## + experience:industry    1      3826 92036741 7183.7
## + married:gender         1      2726 92037842 7183.7
## + experience:south       1      2546 92038021 7183.7
## + married:education      1      2004 92038563 7183.7
## + occupation:married     1      1265 92039302 7183.8
## + south:married          1       542 92040026 7183.8
## + industry:married       1        88 92040480 7183.8
## + south:ethnicity        1        84 92040483 7183.8
## + occupation:south       1        44 92040523 7183.8
## + south:union            1        32 92040535 7183.8
## + smsa:education         1         0 92040567 7183.8
## - industry:south         1   1036703 93077270 7186.4
## - gender:ethnicity       1   1193877 93234445 7187.4
## - weeks:gender           1   1434697 93475264 7189.0
## - union:education        1   1666677 93707244 7190.4
## - industry:union         1   1717323 93757891 7190.8
## - south:education        1   2124837 94165404 7193.3
## - weeks:married          1   2160152 94200719 7193.6
## 
## Step:  AIC=7180.43
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - married:union          1    165016 92309285 7179.5
## - weeks:south            1    170581 92314850 7179.5
## - education:ethnicity    1    170731 92315000 7179.5
## - union:ethnicity        1    203159 92347428 7179.7
## - experience:weeks       1    224369 92368639 7179.9
## - industry:ethnicity     1    229510 92373779 7179.9
## - weeks:smsa             1    250423 92394692 7180.0
## - industry:smsa          1    290321 92434590 7180.3
## <none>                               92144269 7180.4
## - smsa:union             1    321657 92465927 7180.5
## - experience:ethnicity   1    462747 92607016 7181.4
## - smsa:gender            1    475189 92619458 7181.5
## + weeks:ethnicity        1    112127 92032142 7181.7
## + experience:union       1    103702 92040567 7181.8
## + industry:education     1     98925 92045344 7181.8
## + south:smsa             1     90124 92054145 7181.8
## - married:ethnicity      1    534776 92679045 7181.9
## + weeks:industry         1     49411 92094858 7182.1
## - weeks:occupation       1    579448 92723717 7182.2
## + smsa:ethnicity         1     36140 92108129 7182.2
## + occupation:industry    1     31687 92112582 7182.2
## + occupation:ethnicity   1     27711 92116558 7182.3
## + experience:married     1     24594 92119675 7182.3
## + south:gender           1     19692 92124577 7182.3
## + industry:gender        1     18749 92125520 7182.3
## + weeks:education        1     16993 92127276 7182.3
## + gender:education       1     14353 92129916 7182.3
## + experience:smsa        1     14129 92130140 7182.3
## + experience:education   1     13491 92130778 7182.3
## + gender:union           1     12070 92132199 7182.4
## + occupation:smsa        1      9988 92134281 7182.4
## + experience:industry    1      8893 92135376 7182.4
## + occupation:gender      1      8845 92135424 7182.4
## + smsa:married           1      4645 92139624 7182.4
## + experience:gender      1      3679 92140590 7182.4
## + married:gender         1      2580 92141689 7182.4
## + married:education      1      2509 92141760 7182.4
## + south:union            1      2296 92141973 7182.4
## + occupation:married     1      2263 92142006 7182.4
## + weeks:union            1       573 92143696 7182.4
## + smsa:education         1       530 92143739 7182.4
## + occupation:south       1       514 92143755 7182.4
## + industry:married       1       452 92143817 7182.4
## + south:ethnicity        1       251 92144018 7182.4
## + experience:south       1        83 92144187 7182.4
## + south:married          1         1 92144268 7182.4
## - occupation:union       1    674025 92818294 7182.8
## - occupation:education   1    677830 92822099 7182.8
## - experience:occupation  1    759413 92903682 7183.3
## - industry:south         1   1021806 93166075 7185.0
## - gender:ethnicity       1   1164384 93308653 7185.9
## - weeks:gender           1   1418850 93563119 7187.5
## - union:education        1   1585444 93729713 7188.6
## - industry:union         1   1729388 93873657 7189.5
## - south:education        1   2084083 94228352 7191.7
## - weeks:married          1   2163802 94308071 7192.2
## 
## Step:  AIC=7179.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity + education:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - education:ethnicity    1    130462 92439747 7178.3
## - weeks:south            1    158071 92467356 7178.5
## - experience:weeks       1    217312 92526597 7178.9
## - industry:ethnicity     1    237370 92546655 7179.0
## - weeks:smsa             1    245747 92555032 7179.1
## - smsa:union             1    288921 92598206 7179.4
## - union:ethnicity        1    295944 92605229 7179.4
## <none>                               92309285 7179.5
## - industry:smsa          1    330146 92639431 7179.6
## - smsa:gender            1    446533 92755818 7180.4
## - experience:ethnicity   1    451973 92761258 7180.4
## + married:union          1    165016 92144269 7180.4
## + weeks:ethnicity        1    148510 92160775 7180.5
## - married:ethnicity      1    475100 92784385 7180.6
## + experience:union       1    131932 92177353 7180.6
## + industry:education     1     95624 92213661 7180.9
## + south:smsa             1     81610 92227675 7181.0
## + weeks:industry         1     50896 92258389 7181.2
## + south:gender           1     49513 92259772 7181.2
## + smsa:ethnicity         1     40273 92269012 7181.2
## + experience:married     1     36793 92272492 7181.3
## + industry:gender        1     30628 92278657 7181.3
## + gender:union           1     29698 92279587 7181.3
## + occupation:ethnicity   1     28754 92280531 7181.3
## + occupation:industry    1     27167 92282118 7181.3
## - weeks:occupation       1    599334 92908619 7181.3
## + weeks:education        1     20476 92288809 7181.4
## + south:married          1     14669 92294616 7181.4
## + experience:education   1     13927 92295358 7181.4
## + experience:smsa        1     12356 92296929 7181.4
## + occupation:gender      1     11059 92298226 7181.4
## + gender:education       1     10310 92298975 7181.4
## + experience:industry    1      9144 92300141 7181.4
## + occupation:smsa        1      7062 92302223 7181.5
## + smsa:married           1      6069 92303216 7181.5
## + weeks:union            1      4552 92304733 7181.5
## + occupation:married     1      4313 92304972 7181.5
## + industry:married       1      3925 92305360 7181.5
## + married:gender         1      1241 92308044 7181.5
## + experience:gender      1      1040 92308245 7181.5
## + married:education      1       795 92308490 7181.5
## + south:union            1       786 92308499 7181.5
## + occupation:south       1       603 92308682 7181.5
## + south:ethnicity        1       276 92309009 7181.5
## + experience:south       1       132 92309153 7181.5
## + smsa:education         1       116 92309169 7181.5
## - occupation:union       1    652610 92961895 7181.7
## - occupation:education   1    736687 93045972 7182.2
## - experience:occupation  1    794246 93103531 7182.6
## - industry:south         1   1027948 93337233 7184.1
## - gender:ethnicity       1   1140084 93449370 7184.8
## - weeks:gender           1   1343963 93653248 7186.1
## - union:education        1   1571499 93880784 7187.5
## - industry:union         1   1805383 94114668 7189.0
## - south:education        1   2057016 94366301 7190.6
## - weeks:married          1   2200786 94510071 7191.5
## 
## Step:  AIC=7178.34
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:south + weeks:smsa + weeks:married + weeks:gender + 
##     occupation:union + occupation:education + industry:south + 
##     industry:smsa + industry:union + industry:ethnicity + south:education + 
##     smsa:gender + smsa:union + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:south            1    180354 92620102 7177.5
## - experience:weeks       1    235430 92675177 7177.8
## - weeks:smsa             1    245873 92685620 7177.9
## - smsa:union             1    284711 92724459 7178.2
## - union:ethnicity        1    299872 92739619 7178.3
## - industry:smsa          1    308882 92748629 7178.3
## <none>                               92439747 7178.3
## - industry:ethnicity     1    360928 92800675 7178.7
## - married:ethnicity      1    413502 92853249 7179.0
## - smsa:gender            1    421583 92861331 7179.0
## - experience:ethnicity   1    436254 92876002 7179.1
## + education:ethnicity    1    130462 92309285 7179.5
## + married:union          1    124748 92315000 7179.5
## + experience:union       1    123670 92316077 7179.5
## + industry:education     1    109401 92330347 7179.6
## + occupation:ethnicity   1    106522 92333226 7179.7
## + smsa:ethnicity         1    102289 92337459 7179.7
## + weeks:ethnicity        1     94223 92345524 7179.7
## + south:smsa             1     83868 92355879 7179.8
## + south:gender           1     47416 92392331 7180.0
## + weeks:industry         1     38278 92401470 7180.1
## + occupation:industry    1     34419 92405328 7180.1
## + experience:married     1     30821 92408926 7180.1
## + weeks:education        1     21702 92418045 7180.2
## + gender:union           1     16893 92422855 7180.2
## + gender:education       1     16383 92423365 7180.2
## + smsa:married           1     13932 92425815 7180.2
## + experience:smsa        1     13608 92426140 7180.2
## + south:married          1     12828 92426919 7180.3
## + occupation:smsa        1      9584 92430164 7180.3
## + experience:education   1      9184 92430564 7180.3
## + industry:gender        1      8992 92430755 7180.3
## + experience:industry    1      8594 92431153 7180.3
## + occupation:gender      1      6612 92433135 7180.3
## + occupation:married     1      5411 92434336 7180.3
## + smsa:education         1      4562 92435185 7180.3
## + married:education      1      4042 92435705 7180.3
## + weeks:union            1      3543 92436204 7180.3
## + south:ethnicity        1      2902 92436845 7180.3
## + experience:gender      1      2348 92437399 7180.3
## + married:gender         1       937 92438810 7180.3
## + experience:south       1       284 92439463 7180.3
## + occupation:south       1        42 92439705 7180.3
## + industry:married       1        28 92439719 7180.3
## + south:union            1         5 92439742 7180.3
## - weeks:occupation       1    628800 93068547 7180.4
## - occupation:union       1    641294 93081041 7180.4
## - experience:occupation  1    808729 93248476 7181.5
## - occupation:education   1    848339 93288087 7181.8
## - industry:south         1   1062655 93502402 7183.1
## - gender:ethnicity       1   1137670 93577417 7183.6
## - weeks:gender           1   1392707 93832454 7185.2
## - union:education        1   1541359 93981106 7186.2
## - industry:union         1   1869290 94309037 7188.2
## - south:education        1   2111105 94550853 7189.8
## - weeks:married          1   2333196 94772943 7191.2
## 
## Step:  AIC=7177.5
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:smsa + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + smsa:union + 
##     married:ethnicity + gender:ethnicity + union:education + 
##     union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - weeks:smsa             1    172792 92792893 7176.6
## - experience:weeks       1    228245 92848346 7177.0
## - industry:smsa          1    311667 92931768 7177.5
## <none>                               92620102 7177.5
## - union:ethnicity        1    314428 92934530 7177.5
## - smsa:union             1    320885 92940986 7177.6
## - industry:ethnicity     1    355606 92975708 7177.8
## - married:ethnicity      1    399021 93019123 7178.1
## - experience:ethnicity   1    435902 93056004 7178.3
## + weeks:south            1    180354 92439747 7178.3
## - smsa:gender            1    467222 93087323 7178.5
## + education:ethnicity    1    152746 92467356 7178.5
## + industry:education     1    129091 92491010 7178.7
## + occupation:ethnicity   1    123265 92496837 7178.7
## + smsa:ethnicity         1    117568 92502533 7178.7
## + married:union          1    110412 92509690 7178.8
## + experience:union       1    109054 92511047 7178.8
## + south:smsa             1    104762 92515340 7178.8
## + weeks:industry         1     70399 92549703 7179.0
## + weeks:ethnicity        1     54871 92565230 7179.1
## + weeks:education        1     53704 92566398 7179.2
## - weeks:occupation       1    573987 93194089 7179.2
## + occupation:industry    1     48596 92571505 7179.2
## + south:gender           1     33699 92586403 7179.3
## + experience:married     1     32438 92587663 7179.3
## + gender:education       1     19841 92600261 7179.4
## + experience:smsa        1     13817 92606284 7179.4
## + industry:gender        1     12089 92608012 7179.4
## + experience:education   1     10807 92609294 7179.4
## + gender:union           1     10662 92609439 7179.4
## + south:ethnicity        1     10167 92609935 7179.4
## + smsa:married           1      9281 92610820 7179.4
## + experience:industry    1      8659 92611443 7179.4
## + occupation:smsa        1      7799 92612302 7179.4
## + occupation:gender      1      6566 92613536 7179.5
## + occupation:married     1      6098 92614004 7179.5
## + south:married          1      4828 92615273 7179.5
## + married:education      1      4730 92615371 7179.5
## + experience:gender      1      3426 92616676 7179.5
## + south:union            1      2795 92617307 7179.5
## + smsa:education         1      1533 92618569 7179.5
## + experience:south       1      1462 92618640 7179.5
## + married:gender         1      1218 92618883 7179.5
## + industry:married       1       599 92619502 7179.5
## + weeks:union            1        41 92620061 7179.5
## + occupation:south       1         7 92620095 7179.5
## - occupation:union       1    698568 93318670 7180.0
## - experience:occupation  1    821734 93441835 7180.8
## - occupation:education   1    845635 93465737 7180.9
## - industry:south         1   1029459 93649561 7182.1
## - gender:ethnicity       1   1176305 93796407 7183.0
## - weeks:gender           1   1377577 93997679 7184.3
## - union:education        1   1621124 94241226 7185.8
## - industry:union         1   1849255 94469357 7187.3
## - south:education        1   2169719 94789821 7189.3
## - weeks:married          1   2372053 94992154 7190.5
## 
## Step:  AIC=7176.6
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + smsa:union + married:ethnicity + 
##     gender:ethnicity + union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - smsa:union             1    258082 93050975 7176.3
## - experience:weeks       1    288786 93081679 7176.5
## - union:ethnicity        1    296047 93088940 7176.5
## <none>                               92792893 7176.6
## - industry:smsa          1    318661 93111554 7176.6
## - industry:ethnicity     1    359249 93152143 7176.9
## - married:ethnicity      1    398745 93191638 7177.2
## - smsa:gender            1    424866 93217760 7177.3
## - experience:ethnicity   1    442696 93235589 7177.4
## + weeks:smsa             1    172792 92620102 7177.5
## + education:ethnicity    1    147826 92645068 7177.7
## + industry:education     1    141755 92651139 7177.7
## - weeks:occupation       1    487098 93279991 7177.7
## + experience:union       1    130986 92661908 7177.8
## + weeks:industry         1    117791 92675103 7177.8
## + occupation:ethnicity   1    112122 92680771 7177.9
## + married:union          1    110019 92682874 7177.9
## + smsa:ethnicity         1    108883 92684011 7177.9
## + weeks:south            1    107273 92685620 7177.9
## + south:smsa             1     95235 92697658 7178.0
## + occupation:industry    1     51272 92741621 7178.3
## + south:gender           1     36415 92756478 7178.4
## + experience:married     1     36048 92756846 7178.4
## + weeks:education        1     33684 92759209 7178.4
## + weeks:ethnicity        1     27283 92765610 7178.4
## + gender:education       1     21654 92771239 7178.5
## + experience:smsa        1     21014 92771880 7178.5
## + weeks:union            1     20245 92772648 7178.5
## + south:ethnicity        1     12500 92780393 7178.5
## + experience:education   1     11465 92781428 7178.5
## + experience:industry    1     10429 92782464 7178.5
## + industry:gender        1      9947 92782946 7178.5
## + occupation:gender      1      9632 92783261 7178.5
## + gender:union           1      8532 92784361 7178.6
## + smsa:married           1      6176 92786718 7178.6
## + occupation:married     1      5939 92786955 7178.6
## + married:education      1      5182 92787711 7178.6
## + experience:gender      1      4392 92788502 7178.6
## + south:married          1      4323 92788571 7178.6
## + occupation:smsa        1      3772 92789122 7178.6
## + experience:south       1      2443 92790450 7178.6
## + married:gender         1      1535 92791358 7178.6
## + south:union            1      1335 92791558 7178.6
## + industry:married       1      1029 92791864 7178.6
## + smsa:education         1        28 92792866 7178.6
## + occupation:south       1         0 92792893 7178.6
## - occupation:union       1    718100 93510993 7179.2
## - occupation:education   1    871687 93664580 7180.2
## - experience:occupation  1    879035 93671929 7180.2
## - industry:south         1   1063711 93856604 7181.4
## - gender:ethnicity       1   1179928 93972821 7182.1
## - weeks:gender           1   1269071 94061964 7182.7
## - union:education        1   1530461 94323354 7184.3
## - industry:union         1   1781020 94573914 7185.9
## - south:education        1   2084738 94877631 7187.8
## - weeks:married          1   2332192 95125086 7189.4
## 
## Step:  AIC=7176.26
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education + union:ethnicity
## 
##                         Df Sum of Sq      RSS    AIC
## - union:ethnicity        1    233127 93284103 7175.7
## <none>                               93050975 7176.3
## - experience:weeks       1    347031 93398006 7176.5
## - industry:ethnicity     1    360592 93411567 7176.6
## + smsa:union             1    258082 92792893 7176.6
## - smsa:gender            1    374647 93425622 7176.6
## - married:ethnicity      1    413932 93464907 7176.9
## + experience:union       1    201313 92849663 7177.0
## - industry:smsa          1    434838 93485813 7177.0
## - experience:ethnicity   1    436180 93487155 7177.0
## + industry:education     1    157747 92893228 7177.2
## + education:ethnicity    1    146527 92904448 7177.3
## - weeks:occupation       1    482233 93533209 7177.3
## + weeks:south            1    143971 92907004 7177.3
## + smsa:ethnicity         1    113389 92937586 7177.5
## + weeks:smsa             1    109989 92940986 7177.6
## + weeks:industry         1     93822 92957153 7177.7
## + occupation:ethnicity   1     93156 92957820 7177.7
## + married:union          1     84381 92966594 7177.7
## + south:smsa             1     68090 92982885 7177.8
## + south:gender           1     40318 93010657 7178.0
## + occupation:industry    1     40176 93010799 7178.0
## + experience:married     1     37034 93013941 7178.0
## + weeks:education        1     36328 93014647 7178.0
## + experience:smsa        1     25494 93025481 7178.1
## + weeks:union            1     22560 93028415 7178.1
## + weeks:ethnicity        1     21377 93029598 7178.1
## + south:union            1     21062 93029913 7178.1
## + gender:education       1     19660 93031315 7178.1
## + south:ethnicity        1     16236 93034740 7178.2
## + occupation:smsa        1     15800 93035175 7178.2
## + industry:gender        1     14627 93036348 7178.2
## + experience:education   1     13291 93037684 7178.2
## + occupation:gender      1     11935 93039041 7178.2
## + smsa:education         1     11915 93039061 7178.2
## + south:married          1      8997 93041978 7178.2
## + occupation:married     1      7285 93043690 7178.2
## + married:education      1      7076 93043899 7178.2
## + experience:industry    1      6809 93044166 7178.2
## + experience:south       1      5197 93045778 7178.2
## + industry:married       1      4895 93046080 7178.2
## + experience:gender      1      4109 93046866 7178.2
## + gender:union           1      3000 93047975 7178.2
## + occupation:south       1      2392 93048583 7178.2
## + smsa:married           1      2350 93048625 7178.2
## + married:gender         1      1273 93049702 7178.2
## - occupation:union       1    790925 93841900 7179.3
## - experience:occupation  1    861950 93912926 7179.7
## - occupation:education   1    888278 93939253 7179.9
## - industry:south         1   1137537 94188512 7181.5
## - gender:ethnicity       1   1203368 94254343 7181.9
## - weeks:gender           1   1292681 94343656 7182.5
## - union:education        1   1642035 94693010 7184.7
## - industry:union         1   1781824 94832799 7185.5
## - south:education        1   2149198 95200173 7187.8
## - weeks:married          1   2330415 95381390 7189.0
## 
## Step:  AIC=7175.75
## YM ~ experience + weeks + occupation + industry + south + smsa + 
##     married + gender + union + education + ethnicity + experience:weeks + 
##     experience:occupation + experience:ethnicity + weeks:occupation + 
##     weeks:married + weeks:gender + occupation:union + occupation:education + 
##     industry:south + industry:smsa + industry:union + industry:ethnicity + 
##     south:education + smsa:gender + married:ethnicity + gender:ethnicity + 
##     union:education
## 
##                         Df Sum of Sq      RSS    AIC
## <none>                               93284103 7175.7
## - experience:ethnicity   1    342374 93626477 7175.9
## - experience:weeks       1    357898 93642000 7176.0
## - married:ethnicity      1    382852 93666955 7176.2
## - smsa:gender            1    389928 93674031 7176.2
## + union:ethnicity        1    233127 93050975 7176.3
## + experience:union       1    202998 93081104 7176.5
## - industry:smsa          1    431444 93715546 7176.5
## + smsa:union             1    195163 93088940 7176.5
## + industry:education     1    184859 93099243 7176.6
## + occupation:ethnicity   1    174125 93109978 7176.6
## - weeks:occupation       1    454255 93738358 7176.6
## + weeks:south            1    153089 93131014 7176.8
## + education:ethnicity    1    151428 93132674 7176.8
## + married:union          1    147965 93136137 7176.8
## + weeks:industry         1    107772 93176331 7177.1
## + weeks:smsa             1    103363 93180739 7177.1
## + south:smsa             1     84564 93199538 7177.2
## + smsa:ethnicity         1     74635 93209467 7177.3
## + south:gender           1     57275 93226827 7177.4
## + occupation:industry    1     48779 93235323 7177.4
## - industry:ethnicity     1    584573 93868675 7177.5
## + experience:married     1     37345 93246758 7177.5
## + south:union            1     36552 93247551 7177.5
## + weeks:ethnicity        1     33932 93250170 7177.5
## + weeks:education        1     25283 93258819 7177.6
## + weeks:union            1     23454 93260649 7177.6
## + industry:gender        1     18730 93265372 7177.6
## + gender:education       1     17545 93266558 7177.6
## + experience:smsa        1     17496 93266606 7177.6
## + gender:union           1     16562 93267541 7177.6
## + occupation:gender      1     16119 93267983 7177.6
## + south:married          1     15166 93268937 7177.6
## + smsa:education         1     14742 93269360 7177.7
## + experience:education   1     14113 93269990 7177.7
## + occupation:smsa        1      9926 93274176 7177.7
## + occupation:married     1      7830 93276273 7177.7
## + occupation:south       1      4616 93279487 7177.7
## + experience:industry    1      3407 93280696 7177.7
## + south:ethnicity        1      2569 93281534 7177.7
## + experience:gender      1      2249 93281853 7177.7
## + married:education      1      2187 93281916 7177.7
## + industry:married       1      2128 93281974 7177.7
## + experience:south       1       978 93283125 7177.7
## + married:gender         1       875 93283228 7177.7
## + smsa:married           1       476 93283627 7177.7
## - occupation:union       1    770225 94054327 7178.6
## - experience:occupation  1    793944 94078046 7178.8
## - occupation:education   1    794605 94078708 7178.8
## - gender:ethnicity       1   1021861 94305963 7180.2
## - industry:south         1   1150084 94434187 7181.0
## - weeks:gender           1   1244968 94529070 7181.6
## - union:education        1   1764736 95048838 7184.9
## - industry:union         1   1883835 95167938 7185.6
## - south:education        1   2103290 95387392 7187.0
## - weeks:married          1   2214309 95498411 7187.7
## 
## Call:
## lm(formula = YM ~ experience + weeks + occupation + industry + 
##     south + smsa + married + gender + union + education + ethnicity + 
##     experience:weeks + experience:occupation + experience:ethnicity + 
##     weeks:occupation + weeks:married + weeks:gender + occupation:union + 
##     occupation:education + industry:south + industry:smsa + industry:union + 
##     industry:ethnicity + south:education + smsa:gender + married:ethnicity + 
##     gender:ethnicity + union:education, data = mydata2)
## 
## Coefficients:
##            (Intercept)              experience                   weeks  
##              -973.6307                 26.3765                 10.2584  
##            occupation1               industry1                  south1  
##             -1017.3840                251.1260                662.0379  
##                  smsa1                married1                 gender1  
##                35.8154              -1887.1285               1936.9768  
##                 union1               education              ethnicity1  
##               991.7270                 78.5235                165.6754  
##       experience:weeks  experience:occupation1   experience:ethnicity1  
##                -0.5124                  7.2153                 -9.0179  
##      weeks:occupation1          weeks:married1           weeks:gender1  
##                12.7170                 41.4631                -37.1696  
##     occupation1:union1   occupation1:education        industry1:south1  
##              -215.2853                 37.5504               -226.2304  
##        industry1:smsa1        industry1:union1    industry1:ethnicity1  
##              -122.2004               -262.7235                274.1885  
##       south1:education           smsa1:gender1     married1:ethnicity1  
##               -50.7068                207.6874                327.3527  
##     gender1:ethnicity1        union1:education  
##              -570.5685                -60.4342

Acknowledgement


Code on STA108 lecture 26 ~ 29 from professor Chen,Hao

Kutner, Michael H., Applied Linear Statistical Models, The McGraw·HiII Irwin, 2004.

Dalpiaz,David.“Applied Statistics with R”, 1 Sept. 2020, https://daviddalpiaz.github.io/appliedstats/applied_statistics.pdf